Hilarious, but no mere comedy record. Tenacious D -- the duo Jack Black (''High Fidelity'') and Kyle Gass -- attack acoustic guitars with a metal band's intensity, aided by Foo Fighter and fan Dave Grohl on drums, with the Dust Brothers producing. The D have a multitude of messages, most of them unprintable and having to do with wooing women, but also an overriding belief that the purpose of life is to create something aspiring to art, even if it is the magnificently detailed crud of Tenacious D-music. They're profane, bursting with rage and lust, and they deliver more laughs than anyone since Richard Pryor. In short, they are artists with a capital...A.