These days, Jimmy Fallon looks like a true professional clad in a suit and tie as the host of his own talk show where he interviews dignitaries and A-list celebrities. But he does more than just these interviews.

If you have tuned in to The Tonight Show, you know that Jimmy is prone to giggle fits which is often contagious. 

But before his hosting gig on The Tonight Show, Fallon was a cast member on Saturday Night Live (SNL), the legendary late-night program designed to make you burst into uncontrollable peals of laughter and supposedly intended to destroy Fallon as well.

'Jimmy Falloning'

The comedian and talk show host famously broke character on the show through stifled guffaws and outbursts of chuckles and, more often than not, dragged everyone around him.   

However, the disaster was the most enjoyable part of the beloved show as it led to some of the funniest moments in the history of SNL. 

In fact, his inability to stay in character has even inspired YouTube montages and a verb named after him.

Known as 'Jimmy Falloning,' urban dictionary defines it as "Breaking character. Laughing or going out of character while performing an act."

Even though Fallon's character breaking made the sketch every single time, he was both criticized and lauded for his uncontrollable giggle fits. 

In his own talk show, when he was interviewing Robert Pattinson, who was there to promote his new Western comedy Damsel, the two started a discussion on Pattison's foray into comedy. Pattinson then mentioned his favorite comedy movie was Corky Romano, starring Fallon's former SNL co-star, Chris Kattan. 

Fallon then started recounting his experience on the iconic "More Cowbell" sketch. 

....Then Will looked at me, and I saw the eyes of, like, a crazy person. Then I just started laughing and I totally broke. I had one line in the whole scene, and I just totally messed up my line.

'Jimmy Fallon Syndrome' 

In addition to having a verb named after him, the comedian also has an eponymous syndrome. 

According to KKT2, the syndrome is defined "as the moment when one realizes that they are seemingly the only person that hates something or someone that everyone else enjoys and praises because they still harbor memories of when said person or thing used to [be terrible]."

Before Jimmy Fallon was branded as the "beloved" late-night talk show host, he was berated for years for his reputation as the worst cast member in SNL history. After his stint on SNL, the comedian followed his alums' path like Chevy Chase, Will Ferrell, Eddie Murphy, and Mike Myers to become an actor. 

That didn't really happen, though. After landing a few roles on-screen, his movies flopped, and his acting career fell through. 

Some people still remember how lousy he was as a performer and dislike him for it despite his popularity on The Tonight Show, which gave rise to the 'Jimmy Falloon Syndrome.'