Just 'cause he's transiting to Nickelodeon's upcoming "True Jackson VP" doesn't mean he's forgotten what made him famous. GREG PROOPS of "Whose Line Is It Anyway?" props his feet up in Atlanta for four nights. The stand-up and improv comic's accolades include The Nightmare Before Christmas, "Flight of the Conchords" and "Bob the Builder." Through June 14. $25-$33. Thurs.-Sat., 8 and 10 p.m.; Sun., 7 and 9 p.m. Laughing Skull Lounge, 878 Peachtree St. 877-523-3288. www.vortexcomedy.com.