Aaron Karo may be a 20-something comedian, but he's still a guy with his finger on the college pulse. The Penn alum answers all of his e-mails himself and sends Facebook invites to new acquaintances. "I still have a soft spot in my heart for Penn," he confided with a laugh. And with his first visit to Penn in two years, the author of Ruminations on College Life has proven that he's still a college kid at heart.

Last weekend, Karo performed two sold-out shows at World Cafe Live with jokes ranging from the Seinfeldian ("Why is it that step-dads always have one-syllable names?") to the risque (including a closer about condoms with numbing gel). And although some jokes were cringeworthy, Karo's comedic style had Penn students rolling on the floor. Quite possibly the funniest joke of the night was a "you know you're wasted..." list. "If you're dipping Kung Pao Chicken into Guacamole," he said, "you're definitely wasted."

But Karo's story isn't the cliche of the kid who "always knew" that he'd be a performer. The 2001 graduate started out taking classes at Wharton with the intention of working on Wall Street. Like many college freshmen, Karo began his college career partying harder than he ever had before, or ever did afterwards. Unsurprisingly, the nocturnal schedule left Karo with difficulty sleeping on Sunday nights. In order to combat his insomnia, he would send out e-mails to 20 of his closest high school friends with funny thoughts. His friends would forward the messages to their friends, and before long, the column had spread like wildfire. He recalled, "I had people e-mailing me and asking, 'Can you add me to your list?' and I was like, 'What list?'"

After graduation, Karo continued with his plans to work on Wall Street, and he did for 13 months. However, the acquisition of a book deal and a manager made it more lucrative to work in comedy. "It was the easiest first book deal ever," he laughed. "I already had a following, so much of it was already written, and the book had a niche so it was easy to market."

After Ruminations came out in the summer of 2002, Karo left Wall Street and began performing stand-up; although he had never performed onstage, it seemed a logical progression. "I was always the comedian," he confessed, "I was just never onstage." He moved to L.A. six months ago -- "As purely a career move," he protests -- and currently has a pilot for Fox, as well as two other sitcom projects and a show at the legendary Hollywood Improv. And his performance in Philadelphia is part of a DVD special, set to come out this October.

But despite his burgeoning comedy career and frat-boy image, Karo still remains a Wharton boy. "I'm the most Wharton-esque comedian," he said. "I have an Excel spreadsheet with 4,000 jokes color-coded by category." And when it comes to writing down ideas, he's replaced his bar napkins and scraps of paper with voice recorders.

And still, some things remain; he continues to release his monthly column, which he lovingly calls "the last pure form of comedy I can write" and maintains his website himself.

But just because he's moved to L.A. doesn't mean that he's forgotten his roots; with his five-year reunion at Penn only months away, it's clear that we'll be seeing Karo again.