'Big Bang Theory,' 'Girls' Stars on How They Learned They Were Funny (Video)

Mayim Bialik cracked kids up at the bus stop, while Zosia Mamet got (unintentional) laughs during dramatic auditions.

For The Big Bang Theory star Mayim Bialik, her long career as a comedic actress began at the bus stop.

When she was 10, she did a “spot-on mimicry” of a girl in her class, Bialik revealed during The Hollywood Reporter’s comedy actress roundtable.

“I was not cruel at all, and I was actually very friendly with her,” Bialik said. “It was then that I realized the subtle line between mimicking someone to the delight of other people because it's so spot-on but without being nasty.”

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Zosia Mamet (HBO's Girls) said when she was younger, she’d go to drama auditions and people would laugh.

“I thought, ‘What's going on here?’” she said. “Then I started booking comedies and playing silly, witty people. People wanted me to do more of that.”

Veteran Arrested Development star Jessica Walter might be known for comedy, but it wasn't always so.

“I couldn't get a sitcom until I was 40!” Walter said. “I had done only dramatic roles in films, TV and plays. And Ellen Travolta, who was on Joanie Loves Chachi, got me on that show. From then on, I got comedies. Now I'm having trouble getting a drama!”

Kaitlin Olson (FX’s It’s Always Sunny in Philadelphia) got her taste for drawing laughter during plays at summer camp when she was 12.

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“In Alice in Wonderland, there was a crying scene. My parents were in the front row laughing, and I was like, ‘Oh, you like this?’ so I started hamming it up,” Olson said. “That was the first time where I was like, ‘OK, I like everyone looking at me and laughing.’"

Kristen Bell (Showtime's House of Lies) said after her first gig -- a decidedly not funny role as a rape victim on The Shield -- she landed Veronica Mars without knowing it’d have so many comedic elements.

“I didn't realize that what I was doing on the show -- which was snarky -- was considered funny,” Bell said. “People told me, ‘You're kind of a comedic actress.’ I was like, ‘I am?’"

THR's comedy actress roundtable also featured Betty White (TV Land's Hot in Cleveland) and was moderated by THR television editor Lacey Rose and senior editor Stacey Wilson.