A hot-dog eating contest, beer bongs, heavy-metal karaoke: These would seem to be Jack Black's definition of a good time, at least if you assume that the sort of vulgar, uncensored characters the actor has inhabited in films like "School of Rock" and "High Fidelity" bear some relation to who he is off-screen. Anyone who has seen him perform as half of the debauched musical duo Tenacious D, in concert or in the HBO series about the band, knows that this wild-and-crazy guy makes Steve Martin look positively G-rated. But on a recent night off from promoting his latest adventure, "Nacho Libre," the $35 million comedy about the Mexican freestyle fighting sport called lucha libre, Mr. Black revealed another side. [More]