And what a plum gig it was: getting on stage during the bathroom break also known as halftime of Monday Night Football. "The same six people were there every week," says DeRosa, 35.
After a surprisingly short stint, DeRosa's friend decided he liked his day job as a math teacher better. But Joe was hooked. He began honing his craft at the Laff House on South Street.
"I love Philly audiences," the comedian says. "They have this aggressive, blue-collar mentality. Nothing is too offensive or highbrow. You can go in any direction."
For DeRosa, the direction was north, to New York, where he moved in 2001. But it took a rather hard shove to get him out of the ancestral nest.
"I had moved back in with my parents for the second time after college," he says. "My mom said, 'This is the last time.' That door was shut. I didn't know anyone in New York, but I knew I hated every job I had that wasn't doing comedy. You end up saying, 'I have to make this work.' "
Over years of struggle, he developed a distinctive stand-up approach.
"Joe is a great joke writer and also a great storyteller," says JoAnn Grigioni, the vice president of talent and specials at Comedy Central.
"He's able to take things in everyday life that might annoy you and elevate them to a whole new level," she continues. "I think of him as an angry mouthpiece for the small injustices of the world."
Although DeRosa shouts during his act as much as any comic since Sam Kinison, he wouldn't classify himself as angry. He thinks he's merely reflecting the attitudes of a disenchanted generation.
"It's more disappointment than anger," he says. "My parents come from the JFK generation of hope and real social change, and the beacon in the night that will make it all better.
"I just don't think that exists anymore. At all. I don't get up there to shock people. I talk about my own life. I'm very personal on stage and very revealing."
One of the funniest bits in Friday night's special involves nurses and grew out of his mother's hospitalization last year.
DeRosa is calling from his parents' house in Collegeville, where he's paying a visit after 30 straight nights on the road. "You think, 'I'll go stay with my folks where it's quiet,' " he says. "You're ripping your hair out after two days."
But he won't be there much longer. He's about to head out for shows in Boston and Rochester, N.Y. Throughout the interview, a disturbing sound erupts intermittently in the background. It sounds like a walrus in deep distress.
"That's my dad downstairs moaning," DeRosa says. "He went to the dentist today, and they pulled seven teeth out of his mouth."
Hey, Boston, get ready for some dentist jokes.
Innocent People: Beware of Joe DeRosa
12:29 a.m. Saturday on Comedy Central
Contact David Hiltbrand at 215-854-4552 or firstname.lastname@example.org, or follow on Twitter @daveondemand_TV.