Jon Stewart called it When Aging Comedians Attack. The event was the taping of the MTV special 25 Lame, which features Stewart, Janeane Garofalo, Denis Leary, and Chris Kattan counting down the 25 worst videos in history, as voted by more than 50,000 MTV viewers. But the most dangerous participant in the special turned out to be washed-up rapper Vanilla Ice. Since the top 10 offenders including Don Johnson's ''Heartbeat'' (No. 1) and Eddie Murphy's ''Whatzupwitu'' (No. 3) were forever banned from MTV, the comics destroyed the videos using a cigarette lighter, hammer, and blender. But when the network asked Vanilla Ice to do the honors for his own ''Ice Ice Baby'' (No. 9), the Iceman, who showed up at the April 30 taping in a Dr. Evil T-shirt, took a baseball bat not only to the ''Baby'' videotape but also to the entire set, leaving cast and crew in shocked silence. Stewart even suffered a cut on his hand from flying debris. ''I could care less,'' Ice says of being included on the lame list, adding that going ballistic was a last-minute choice. ''I was genuinely afraid,'' says Garofalo. ''I thought he was seriously going to get really angry on a channel that embraced him and then turned and mocked him.'' No that'll be Jesse Camp's job.