I honestly never thought things could get worse than "Alf," but tonight, Justin Bieber makes his acting debut—not on "Sesame Street" or "Dancing with the Stars," but on a real show: "CSI." 9 p.m., CBS. I'm tempted to Tivo it just to see if his castrada voice makes all of the glass in my apartment spontaneously shatter... I'm assuming the storyline is that he's being arrested for that god-awful shag haircut. It is, after all, a crime against nature.