Improvisers have never been particularly prudish--in fact, improvisatory games tend to dissolve inhibitions. And in recent years, as audiences' general knowledge has shrunk (at one show, a reference to Ernest Hemingway was greeted with the stunned silence usually reserved for quips about high-energy physics), jokes about sex and bodily functions have become a quick, easy way to get everyone's attention. Improvisers often have to battle the urge to "go blue," as they say in the business, and sometimes censor themselves too strictly. The folks at The Hot Karl have come up with another solution: they revel in shamelessness. As emcee Tim Chidester proudly announces at the beginning of each show, it's totally uncensored. The irony is that once the performers are free to say and do anything, they become less obsessed with sex and more interested in creating strong scenes and characters. So despite the assertions that all they're doing is creating the vilest improv they can think of, they summon up the kind of witty scenes other improv troupes would kill for. Certainly that intelligence explains why, after three years, The Hot Karl still packs 'em in every Saturday at midnight. On August 31, The Hot Karl celebrates its third anniversary with a show that features special guests and a farewell appearance by original cast member Frank Caeti. ComedySportz, 2851 N. Halsted, 773-549-8080. Open run: Saturdays, midnight. $10.