MIKE BIRBIGLIA didn't always want to be a comedian. He originally wanted to open a pizzeria to celebrate his Italian heritage. (Though he jokes that his family "isn't real Italian, they're like Olive Garden Italian.") Nevertheless, he had too much talent, so rather than letting it go to waste he moved to New York City to pursue comedy. Eventually, an invitation to perform on David Letterman opened doors to shows at the Montreal Comedy Festival and on Comedy Central. He's now a nationally headlining comic, stopping in Atlanta for a four-day booking at the Punchline Thurs.-Sun., JUNE 14-17. $17.50-$19.50. Thurs., 8 p.m.; Fri., 8 and 10 p.m.; Sat., 7 and 9 p.m.; Sun., 8 p.m. 280 Hilderbrand Drive. 404-252-5233. www.punchline.com.