Nothing bolsters one's career like publicly insulting a well-established celebrity. Comedian Don Rickles learned that much in 1957, when he poked fun at Frank Sinatra's penchant for pugilism -- while Ol' Blue Eyes was in the audience (OK, so maybe that doesn't work for hand puppets picking on Eminem). But it wasn't until his 1965 Tonight Show appearance that Rickles proved that middle America would dig his unusually acerbic style. Of course, insults are the industry standard nowadays, and celebrity roasts are highly prestigious events for the comedy elite. And it all started with a bald-headed guy who couldn't take being heckled. The "Merchant of Venom" performs tonight and Thursday at the Seminole Hard Rock Hotel & Casino (1 Sem-inole Way, Hollywood). Show starts at 8 p.m., and tickets cost $50. Call 954-523-3309.