Years ago, MICHAEL MCDONALD left his straight-laced job as a businessman and loan officer to try his hand at comedy. And now, after 10 seasons with "MADtv," he's making another change, leaving the popular sketch comedy show to take his repertoire of amazing impressions and hilarious stand-up on the road. He's best remembered for such unforgettable characters as Bible Dude and Ronald Goddard, child genius, as well as his spot-on impressions of a wide range of celebrities, including Simon Cowell and Bill O'Reilly. McDonald's debut at the Punchline brings the talent he showcased on "MADtv" to a new audience. $20. Fri., 8 and 10 p.m.; Sat., 7 and 9 p.m. 280 Hilderbrand Drive. 404-252-5233. www.punchline.com.