In 2004, few could have imagined that Harold and Kumar Go To White Castle would end up being one of the most popular films of the year. While not just being a box office hit, it was worthy of two more sequels. Yet, 16 years later after first gracing the big screen, the cult classic, turned mainstream phenomena, still has a place in fans' hearts.

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The film franchise has led to the creation of thousands of Facebook memes along with being a commercial success for White Castle. Not to mention that it is at the top of the list when it comes to millennial stoner comedies.

Goldstein and Rosenberg Have Shakespearean Origins

A stoner comedy about two guys searching for a burger restaurant is probably the last place one would expect to find Shakespearean references, yet, fans might be pleasantly surprised as the characters of Goldstein and Rosenberg were partly based off of Hamlet's Rosencrantz and Guildenstern.

Besides the Shakespearean similarities, both Goldstein and Rosenberg were also supposed to be a depiction of Jon Hurwitz and Hayden Schlossberg who grew up together in a small town in New Jersey. The writers intended on both characters being Jewish to show the reflection of friends they had in their own lives.

Neil Patrick Harris Spin-Off

For a man who fell off the edge of the world after Doogie Howser MD, Neil Patrick Harris wasn't a popular figure for most of the 1990s and early 2000s. At least, until he accepted the role of himself in Harold and Kumar Go To White Castle.

His career was instantly rejuvenated, bringing him the fame that he never had with any of his past roles. The directors of the film Jon Hurwitz and Hayden Schlossberg loved his character so much in the film, they have even considered making a spin-off with his character as the main protagonist.

Kal Penn's White Castle Veggie Burgers

A fun fact that many fans might not know, is that the actor that plays Kumar, Kal Penn is a vegetarian. This might seem like quite a dilemma for the directors, having a vegetarian that is supposed to be addicted to hamburgers in the script.

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Yet, they managed to find a creative way to work around it by making soy-based burgers that looked like White Castle burgers for him to eat while filming. The idea turned out to be a success, as Penn was able to stay true to his vegetarian beliefs while playing his role in the film.

Neil Patrick Harris Was Written Into The Movie Without Him Knowing

The Harold and Kumar movies wouldn't be the same without the out of control, sex-crazed Neil Patrick Harris. However, Harris said that he was completely unaware of the movie until a friend told him he had a part in it.

Curious, he got in touch with the writers who explained, that yes, they have him in it, only to then ask if he would want to be in it. He agreed to the part so long as he had full control over any changes or concerns he had of the way he was portrayed in the film.

White Castle Promoted The Film

Harold and Kumar eat White Castle burgers in Harold and Kumar Go To White Castle

There is nothing better than a free advertisement, especially when that advertisement is a full-length cinematic film's premise revolving around two guys obsession with the fast-food chain. While some companies like Krispy Kreme refused to be part of a stoner comedy, White Castle publicized their restaurant's part in the film by creating and selling commemorative Harold and Kumar Go to White Castle collectible cups.

They then took it a step further by inducting John Cho and Kal Penn into the White Castle Hall of Fame to make sure that the film and the fast-food chain were forever intertwined.

Penn's Allergic Reaction Scare

One of the scariest facts to learn about Harold and Kumar go to White Castle was that Kal Penn almost died playing his iconic role. In one scene to create dust coming out of a ventilator shaft, the crew grounded up walnuts.

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Unknown to them, Penn is highly allergic to nuts causing him to instantly break out once he inhaled the dust. Luckily, he realized what was happening and quickly took Benadryl to stop the swelling from progressing. After remaining in fresh air for over two hours, he finally was able to get back to work.

Penn and Cho Made $75,000 Each In The First Film Of The Franchise

When fans think of a Hollywood film, they can't help but imagine the millions that each actor or actress brings in but, in Harold and Kumar Go To White Castle, both actors were fairly new to the scene.

Since they didn't have the name recognition that would deliver them a handsome paycheck, they instead received $75,000 each for their roles in the film. Penn stated in an interview with CNBC that by the time he got done paying his agent, he was left with just a little over $22,000.

Jon Hurwitz Grandparents Brought Him Frozen White Castle Burgers

Writer and director Jon Hurwitz admitted he might have been a little spoiled by his grandparents when they used to come to visit him. He claimed that while living in Pittsburgh, his grandparents would fly in to see him.

Before dropping by, they would buy 120 frozen White Castle burgers for him to eat. Since White Castle burgers weren't sold in stores at the time, they had to order the burgers at the restaurant. So it isn't too surprising that Jon Hurwitz would incorporate his love for White Castle in his films.

Kal Penn Left White House Role To Star In A Very Harold And Kumar 3D Christmas

After the first Harold and Kumar movie, Kal Penn accepted a role in the Obama Administration as an associate director in the White House of Public Engagement. During his time in the Obama Administration, Penn announced that further Harold and Kumar movies would have to be postponed until his time in the administration was over.

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However, in 2010, Penn reversed course, temporarily resigning from his position so that he could star in A Very Harold and Kumar 3D Christmas. After the movie was completed, he returned to his former role within the administration.

All Three Films Had A Budget of $40 Million

A budget of $40 million might sound like a lot of money but by Hollywood standards, it is chump change. When New Line Cinema released the first Harold and Kumar movie back in 2004, they didn't have high expectations.

While the film turned out to have later success, at the time it was in theaters it only grossed $23 million worldwide, placing it in the bust category. However, even as the film's popularity grew, the budgets for the two sequel films remained the same. Unlike the first film, the next two proved to be box office gold.

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