American Pie turns 19 this year, which makes it older than most of the characters in the film (though quite a few years younger than the actors that played them). To celebrate, it's time to take a trip down memory lane and re-visit some of those classic American Pie moments that defined a generation.

Who can forget the time Mr. Levenstein caught Jim making sweet, sweet love to that apple pie? Or the time Stifler drank the beer that was... uh, tainted by Kevin? Or how about the time the R-rated franchise was marketed to children? Huh? Or when the original film's writer was sued by his talent agency for not paying the agency's commission? Wait, what?

That's right, the American Pie franchise may be a fun coming-of-age tale about sex and teenage angst on-screen, but the goings-on behind-the-scenes are a different story entirely.

From the difficulty the first film had finding a director, to actors getting in all sorts of trouble with the law, the American Pie franchise is full of secrets the producers and cast would like to keep from seeing the light of day.

Here are the 15 Secrets You Didn’t Know Behind The American Pie Franchise.

15. No one wanted to direct the first movie

American Pie's journey from screenplay to the big screen was a long one. Adam Herz wrote the original screenplay in just six weeks and shopped it around with the title, Untitled Teenage Sex Comedy That Can Be Made For Under $10 Million That Most Readers Will Probably Hate But I Think You Will Love (seriously, that's what he called it).

The screenplay eventually sold for $650,000 to $750,000 and the next step was finding a director. Unfortunately, that was a tall task since no one wanted the job.

According to executive producer Craig Perry, 70 people were sought before the movie eventually landed brothers Chris and Paul Weitz as co-directors. According to Chris, "nobody else wanted to direct it—literally nobody."

Though the film did eventually go on to be a huge success, it's got to be a sore spot for the producers to have so many directors initially turn down the project.

14. Eugene Levy hated the script and thought his character was creepy

Eugene Levy is one of the best parts of the American Pie franchise. (He also happens to be the only cast member to appear in every one of the franchise's movie.)

fHis performance as Jim's loving, yet incredibly corny father Noah Levenstein is simply brilliant; a fact that is made all the more impressive when you realize Levy improvised most of his dialogue.

According to Levy, "I didn’t really like the part the way it was written...[it] was a little creepy. So I made him more square."

Levy said he wanted to make the character feel like a real dad who cared about his son so he sat down with the directors and Jason Biggs and improvised his scenes. The result is what we see in the film.

It's great when an actor can improvise a great character. It's not so great when they do so because they didn't like the script.

13. Stifler is based on a guy in jail

It's not unusual for writers to base characters on people they've known in real life. In fact, it's quite common.

For example, J.K. Rowling based Severus Snape on her old chemistry teacher and the soup Nazi in Seinfeld was based on soup-maker Ali "Al" Yeganeh. As it turns out, Steve Stifler (the crude and rude jock played by Seann William Scott) is loosely based on Adam Herz' high school classmate, a man by the name of Brian Krebs.

Herz and Krebs both graduated from East Grand Rapids High School in 1991. Unfortunately, the real Krebs is currently in prison on second-degree charges for ending someone one else's life, which stemmed from a stabbing in 2011.

Herz denies Stifler is based on Krebs, but two people familiar with the screenplay admit the connection is there. Given the circumstances, it's understandable why Herz would try to distance the character from the man.

12. A body double had to be fired while on set

Body doubles are a huge part of the film industry. Most of the time body doubles are used for scenes that include dangerous stunts (unless the actor is kick-butt like Tom Cruise or Charlize Theron). Other times, they're used in adult scenes when actors would rather not bare their private parts for the world to see.

This was supposed to be the case for American Pie, specifically the adult scene between Jason Biggs' Jim and Alyson Hannigan's Michelle. As one might guess, one of the requirements for being a body double is having a body that can double as that of the actor.

Apparently the body double for Jason Biggs didn't get the memo because he showed up on set with an eight-inch scar across his stomach. He was promptly fired.

Hiring a body double without confirming whether or not his body could double for the actor's is definitely not the casting agent's best moment.

11. A large percentage of the opening weekend's audience were probably underage

American Pie premiered in theaters on July 9, 1999 and made $18.7 million in its opening weekend. While that figure is impressive, box office numbers from that weekend suggest the movie's total should have been much higher and that many underage viewers snuck into the theater after buying tickets to another film.

That movie is Tarzan, which premiered on June 16. The film saw an 18.2% drop in its box office its second week in theaters and a steep 51.9% drop in its third. Then it miraculously rebounded in its fourth, dipping just 17%. What major film happened to premiere that week? You guessed it, American Pie.

There's no way of proving underage audiences purchased Tarzan tickets and then snuck in to see the R-rated comedy, but the proof is in the box office pudding. The week after American Pie hit theaters, Tarzan's box office number returned to normal.

10. The wrong Blink-182 drummer was credited

One of the more memorable moments in the first film occurs when Jim decides to commit a felony by secretly recording Nadia changing clothes in his bedroom and broadcasting it to his friends via webcam. Unfortunately for Jim and Nadia, the stream goes out to people far beyond Jim's social circle.

The film cuts between Kevin, Finch, Stifler, and others watching the stream until familiar and unexpected faces appear on screen: members of the band Blink-182. The band had released its third studio album (Enema of the State) the previous month and so its members were tapped for cameos.

The three are credited at the end of the film as Mark Hoppus, Thomas M. DeLonge, and Scott Raynor. The only problem here is the drummer who actually appeared in the film is Travis Barker. Raynor was the band's original drummer but had since been replaced by Barker. Oops.

9. Universal Pictures likely lost millions by selling the foreign rights

When American Pie first hit theaters in 1999, there was no telling how the film would perform at the box office. After all, the original script had been written in just six weeks and the cast was largely made up of a bunch of unknowns.

Even if the movie did well in the United States, there was no guarantee it would do the same abroad, which is why Universal sold the foreign distribution rights.

With this decision, Universal was betting that the film would flop overseas. American Pie did just the opposite, raking in $132 million at the foreign box office. A month before the film's release, at least one studio executive called Universal's decision to sell the foreign distribution rights "moronic."

The executive said selling these rights on a film with such a low budget made little financial sense. Considering American Pie's massive box office, this is one decision Universal definitely regrets.

8. American Pie 2's condom controversy

After American Pie turned into a monster hit, it was only a matter of time until American Pie 2 came to fruition. The movie was shot in 2001 with a budget of $30 million (roughly triple its predecessor).

Seeing an opportunity for crossover marketing, Ansell Healthcare (the makers of Lifestyle condoms) reached out to Universal about the possibility of producing commercials that would link Lifestyle condoms to the film.

Universal originally agreed to the deal but ultimately backed out because the Motion Picture Association of America (MPAA) doesn't allow commercials featuring condoms to be seen by general audiences.

Carol Carrozza, vice president of marketing at Ansell, said Universal's decision to back out of the agreement perpetuated a "double standard — using flagrant intimacy to sell and entice young people while denying them information about products that can protect them." There's no denying that Carrozza makes a strong point.

7. An American Pie 2 trailer was shown before a kid's movie

It should come as a surprise to precisely no one that films made for a particular audience often feature trailers for other films made for that audience.

This is why every Marvel movie shown in theaters usually includes a trailer for three future Marvel movies, a DC movie, and three or four other action films. The rationale is simple: if you like this movie, you'll probably like these too.

Sure a trailer for a romantic comedy or a kid's film will pop up every now and then, but rarely ever do you see a trailer attached to a film marketed to a completely different audience. So of course a trailer for American Pie 2 was shown before Atlantis: The Lost Empire. Why wouldn't it be?

American Pie 2 was technically unrated at the time, but that doesn't change the fact that it was sneakily marketed to children.

6. There are eight movies in the franchise (four of them are terrible)

Let's count together: American Pie, American Pie 2, American Wedding, American Reunion, and four awful films no one wants to discuss. That's right, there are eight movies in the American Pie franchise.

Between the theatrical releases of Wedding and Reunion, the franchise release four direct-to-dvd sequels featuring none of the original cast members (with the exception of Eugene Levy).

Each of the films is more loosely connected to the original trilogy than the last. American Pie: Band Camp centers around Stifler's little brother Matt, while American Pie: The Naked Mile and American Pie: Beta House shifts focus to Stifler's cousin Erik.

American Pie: The Book of Love is about the book Kevin received from his older brother in the original movie-- talk about bleeding a franchise dry.

After the four films were roasted by critics, the producers came to their senses and brought the original cast back together for 2012's American Reunion.

5. Chris Klein (and others) were purposely left out of American Wedding

There's no denying the appeal of the first two American Pie movie comes from the cast. Jim, Oz, Kevin, Finch, Stifler, Vicky, Michelle, Heather, and Nadia make a fascinating group of characters, and their interactions with one another add to the audiences enjoyment of the movies. So when half of the cast was missing from 2003's American Wedding, it was a bit jarring.

The absence of Vicky, Heather, and Nadia is forgivable since the first two had little connection to Jim and Michelle, and it doesn't make any damn sense for Michelle to want Nadia to be at her wedding. Oz, however, was one of Jim's closest friends and should have been present.

According to Chris Klein, he was never invited to reprise his role in American Wedding, which is odd. It's not often a main character is so obviously snubbed from a sequel only to be brought back later on in the series.

4. A writer was sued by his talent agency over profits

Adam Herz wrote the original American Pie and is also credited as co-producer. He would go on to write and produce American Pie 2 and American Wedding, during which time he was represented by the United Talent Agency.

Before the third movie went into production, UTA allegedly negotiated a deal on Herz' behalf for "millions of dollars as well as a right of first negotiation on any subsequent sequels and remakes with a guaranteed compensation package".

When American Reunion was greenlit in 2011, Herz opted not to write the film, but was still compensated as a producer due to the deal negotiated by UTA. For negotiating the deal, UTA claims it was owed ten percent of Herz' compensation, which he refused to pay. As a result, UTA sued Herz in 2011.

It's unknown whether or not UTA won the lawsuit, but it did win a similar lawsuit against director Barry Sonnenfeld.

3. American Reunion bombed in the U.S.

The American Pie franchise has had quite a performance at the box office since the original film was released 19 years ago.

The first movie grossed an incredible $102 million at the U.S. box office on a budget of $11 million. American Pie 2 followed that up with $145 million on a $30 million budget, and while American Wedding didn't perform as well as its predecessor, it still made $104 million on a $55 million budget.

Then came the awful direct-to-dvd sequels that were likely cheap and easy to make, and likely turned a profit. After that, the original cast was brought back together for 2012's American Reunion, and the film bombed domestically.

While the original trilogy of movies each grossed over $100 million at the domestic box office, Reunion only made $57 million on a $50 million budget. Needless to say, the bloom was off the rose.

2. Substances, rehab, and run-ins with the cops

The American Pie franchise has no shortage of talented actors. Unfortunately, those actors have had no shortage of behind-the-scenes problems either.

The actor with perhaps the most well-known issues is Natasha Lyonne, who has had a number of run-ins with the law and developed a heroin addiction in the mid-2000s. Thankfully, she has since cleaned up her life and is now a series regular on Orange is the New Black.

Lyonne isn't the only cast member with skeletons in her closet. Seann William Scott and Chris Klein have also had their fair share of issues.

Scott voluntarily entered rehab in 2011 for "health and personal issues," and Klein was arrested for drunk driving in 2005 and then again in 2010. A week after his second arrest, Klein began a 30-day alcohol addiction program.

No cast is squeaky clean, but having three caught up in substances, run-ins with the law, and rehab isn't ideal either.

1. Most of the cast has had little success outside of the franchise

An undeniable, cold, hard fact to come out of the American Pie franchise is that most of its actors have had little success outside of the franchise that made them household names (for a short while at least). Considering how wildly popular the first two films were, it's shocking the franchise didn't produce more leading men and women.

Alyson Hannigan and Seann William Scott are undoubtedly the most successful of the bunch, with the former starring in the uber-successful How I Met Your Mother for nine years, and the latter landing a few starring roles in the mid-2000s.

Hannigan has failed to land major film roles, however, and Scott has struggled to shake his Stifler persona.

Jason Biggs landed a few leading roles following the success of the first film, but most of those films flopped, hurting his star power. Meanwhile, the rest of the cast has slowly faded from the limelight.

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Are there any other dark secrets behind the American Pie franchise that we missed? Let us know in the comments!