In Penny's eyes, Sheldon, Leonard, Howard, and Raj are geniuses. They are all professionals in their field and have fun learning about their studies. However, just because this group has high IQs doesn't mean they make perfect life decisions. The entire gang is guilty of doing stupid things from time to time, but that's what made The Big Bang Theory a successful sitcom.
Over the years, the friend group has made quite a few mistakes. More than that, they've done things that could have altered their lives forever. It proves that as smart as these "brainiacs" are, even the smartest people make mistakes.
Howard Slept With His Cousin
Before Howard fell in love with and married Bernadette, he was the ultimate creep. He flirted with any woman that looked in his direction and was relentless. Penny finally put him in his place one day, which stopped his flirtation with her but not necessarily with other women.
During Howard's bachelor party, Raj released a secret that Howard would never want out: he lost his virginity to his second cousin in the back of his car. We all knew Howard was desperate but we didn't know he was desperate enough to sleep with a family member.
Leonard Cheated On Penny
TBBT fans thought Leonard was joking when he told Penny on their wedding night that he kissed another woman while away at sea. Penny was Leonard's dream girl. He finally had the life he wanted with her and he was about to throw it all away for a second of passion? It didn't make sense for his character.
To make matters worse, Leonard told Penny this news while they were driving to the altar to get married! Penny told him she could get past it but after she learned that he still saw the woman he kissed at work, her feelings changed. It was a terrible betrayal of her trust and very unbecoming of Leonard.
Raj Spoiled His Ladies Too Much
While Raj splashing his family's wealth on his dates doesn't sound too bad, that all changed when he met a woman named Emily. Raj was so hopelessly in love that he was willing to do anything to keep Emily around. He finally found a woman he could literally speak to.
He leased her a car, he paid off her credit card, and he bought her diamond jewelry! But when Raj's dad saw how much his son was spending, enough was enough. It was her or the family.
Shockingly, Raj chose "love" over his family's fortune. He didn't even know the woman for more than a month and he was willing to risk it all for a chance with her. After Emily found out Raj was broke she broke up with him. As usual, Raj went on a downward spiral of sadness after.
Howard Agreed To Go To Space Without Talking To Bernadette
It's the honor of a lifetime to be chosen to go to outer space. For Howard, it proved that his knowledge of engineering was strong enough that he was needed in the space station. Even Sheldon couldn't insult him for his accomplishment.
Where Howard went wrong, however, is when he accepted the mission to space before talking to his fiancée... Bernadette had a say in the matter and deserved to have her thoughts and fears known. Howard was only thinking of himself and not how his decisions impacted his loved ones. It all worked out in the end, but perhaps Bernadette would have reacted differently if Howard kept her in the loop from the beginning.
One Night With Penny & Raj
What on earth were Penny and Raj thinking when they fooled around after one too many glasses of wine? Raj always had a secret crush on Penny — who didn't? — but to act on his feelings was incredibly audacious considering Penny is his best friend's on-and-0ff ex-girlfriend.
At the same time, Penny is also to blame. She knew a night with Raj would impact him forever and he wouldn't be able to move on as easily as she would. Raj is clingy and falls in love with any woman who kisses him. Their night together (even though they didn't go "all the way") could have ruined the group's dynamic, their friendship, and both of their relationships with Leonard.
Penny Didn't Realize She Married Someone...
Penny isn't the smartest one in the group but she's not dumb. She has more life experience and a better grasp of the real world than Sheldon and Leonard do. This is why it was surprising when she let it slip that she didn't know Las Vegas weddings were real. She thought they were a joke, which is why she and her ex-boyfriend Zack got hitched while they were in Vegas together.
Leonard totally lost his cool because it spoke volumes about Penny's character. No matter how drunk Penny and Zack might have been, they still had to sign the paperwork solidifying their marriage. Penny was lucky that Zack also thought the wedding was a joke and didn't realize it was real.
Howard & The Mars Rover
When Howard met Dr. Stephanie Barnett, he enticed her with a chance to drive the Mars Rover. This was the only reason Stephanie left the bar with Howard, because who wouldn't want a chance to drive a car on Mars?
Unsurprisingly, Howard's attempt to keep Stephanie around failed miserably. He ended up getting the car stuck in a ditch on Mars, which launched an entire investigation. Howard could have easily lost his privileges and been thrown in jail for using United States space equipment like a toy. He should thank his lucky stars they never found out who did it.
Sheldon's Unknowing Sexual Harassment
Sheldon is a brilliant man, but he doesn't understand basic things that cross the line or that are inappropriate in a work environment. It's because of people like Sheldon that companies and schools have a human resources department.
There have been multiple episodes where Sheldon's ignorance landed him in trouble. He compared his assistant to an egg salad sandwich, he talked about her time of the month, and he ratted his friends out for their poor behavior while he was scolded for his. If this took place in 2020, Sheldon would have been fired. There's no place for sexual harassment in the workplace, even if he didn't realize it was happening.
Howard & Raj At The Top Model House
When Howard and Raj found out about the show America's Top Model, they were in a trance. There was a house in the Los Angeles area that housed gorgeous potential models. The two friends tried finding out where the models were living but when their work failed, they took things up a notch.
They got military-grade satellites involved and located the house. Not only is that incredibly illegal, but it's also super creepy. To make matters worse, the guys actually showed up at the house dressed as fake workers!
Sheldon Drinks Alcohol At The Worst Times
Sheldon doesn't drink alcohol or caffeine. He's not going to do anything that allows him to lose control of his brilliance and he's far too reserved to allow himself to let loose. However, there were rare moments where Sheldon did drink alcohol that could have ruined his reputation forever.
In one episode, he won an award at Caltech but the only way he could accept his award was if he gave an acceptance speech. To calm his nerves, Sheldon drank some wine. But when it was time to give his speech, he was wasted. He was so drunk that he dropped his pants and mooned the audience! As a reputable man in science and at the university, this could have tarnished his career forever.