Think of: A sharp wit in the style of Patton Oswalt with an easy, confident stage presence. Petersen is versatile: He's a talented joke writer, but he can also improvise in the moment.
What caught our eye: An off-the-cuff, middle-of-the-week hosting gig at the now defunct Mottley's during which Petersen made a small crowd laugh enough to sound like a full house. Petersen also played the 2012 Great American Comedy Festival in Norfolk, Neb., which honors the memory of Johnny Carson.
Light-bulb moment: At 17, seeing Patton Oswalt's one-hour special "No Reason to Complain" on Comedy Central. "It hit me in a way that you went, oh, this guy does this for a living, and he does it on TV right now. Look at how much fun he's having talking about things that I'm interested in. But he's doing it in a very funny, intelligent, unique way. He's not a clown. You can be different and original and do this."
Biggest thrill: A show at a Chinese-food buffet that resulted in a fistfight when Petersen took on a table full of hecklers who then rushed the stage. Other comics and audience members joined the fray. After the troublemakers were thrown out, the guy running the show wanted to call it a night, but Petersen refused. "I said, 'We just fought people to have this show. You can't take that away.' And I said to the audience into the microphone, 'You guys want a goddamn show, right?' And they all cheered. I did a half an hour after that, and it was one of the best shows I've ever done."
Biggest surprise: The darker side of show business. "You lose friends over something that's not in your control, just because you might get a little bit of success and they didn't, they don't talk to you anymore. They don't like you. It becomes competitive. Comedy should never be competitive."
Inspired by: Petersen admires Richard Pryor and George Carlin but also credits his father as an influence on his humor. "Probably the funniest person I know. He'll say inappropriate things at the most inappropriate times. That's a huge influence. He's a pretty quick guy, and he'll cut you down verbally as well as physically. He's like 'Stone Cold' Steve Austin, but 5-foot-4."
Aspires to: "I just want to be able to do this everywhere. Headline and get on the stage. I don't want to make millions, I just want to be up there. I love it."
For good luck: Petersen doesn't have any current rituals, but he did once follow advice from a book on standup that said to keep a charm in your pocket, supposedly to build confidence. He chose an old sparking wheel. "It's like a toy from the 1930s, like what they gave kids so they didn't think about the economy. I put that in my pocket once, and it was super-tight button-fly jeans. I was getting fatter. It looked like I had a penguin in my pants."
What people should know: There is nothing that can't be talked about in some way or another. "If we didn't talk about oppression in 1775, we would still be ruled by England. If we don't talk about the crazy acts of security that go on now in the country, we may lose more freedoms than ever."
Coming soon: Petersen will be among the comics performing standup Sept. 7 at ImprovBoston as part of the Boston Comedy Arts Festival.