He was so stressed he couldn't stop chugging water.

Kenan Thompson Rachael Ray Show
Rachael Ray Show/Youtube
| Credit: Rachael Ray Show/Youtube

If you've watched SNL at any point over the past 16 years, odds are good you've cracked up at a Kenan Thompson sketch. This comedian who got his start 25 years ago as a child actor on Nickelodeon's All That is SNL's longest-running cast member—his 16 years on the show surpass Darrell Hammond's 14. 

Although Kenan is now the most senior cast member, he hasn't forgotten about when he got his start. He was in his mid-30s and hoping to get a much-sought-after spot on SNL. 

"I had to do stand-up, and I'd never done stand-up before," he told Rach during an appearance on the Rachael Ray Show. "I was just a working kid actor." 

So Kenan went to a New York comedy club where the stage was "half the size of this table" to give it his best shot. He struggled. Hard. 

"I just didn't understand how to engage with, like, 'Don't you hate airplanes?' or 'That bathroom splash is really annoying,'" he says. 

In other words, the whole off-the-top-of-your-head part of being a stand-up comic just wasn't clicking with him. He got so nervous that all he could do was drink water. "I kept drinking water, but I was never quenching my thirst, so I was drinking out of the bathroom sink," he said. "I was panicking so hard." 

But it worked out. Kenan went on stage, acted like his weird, quirky self and people liked it. 

"I got the job. We're good. But yeah, it was terrifying."

Kenan brought his acting and comedy career full circle this year when he accepted the role of executive producer for a revival of All That, which premiered June 15.

Watch the rest of Kenan's appearance on the Rachael Ray Show here!