The true spirit of Tenacious D is actually captured quite accurately in the other reviews on this site (well, the fanatical ones anyway). For the uninitiated, I'll try to clear things up. Tenacious D is composed of two guys, Jack Black & Kyle Gass, who have a two man band in which they both play acoustic guitar and sing (though Jack is the primary singer). They play some bizarre hybrid of heavy metal and folk. All their lyrics center around how they are truly the greatest band in the universe and have incredible, unfathomable sexual prowess. All of this is sung with 100%, almost hyper-conviction. This is, basically, the joke. I was never a big fan of them live, or their whole act in general (it's amusing and unquestionably original in presentation, but I feel it wears kinda thin fast). However, when Bob Odenkirk and David Cross (and their creative team) from "Mr. Show" got a hold of them for a group of shows for HBO, they transformed the concept into something even better. The show, which presents the two as two out-of-work oddballs who get into all sorts of screwy adventures in between gigs, is as hilarious and out-of-left-field as "Mr. Show" (which is saying something, as "Mr. Show" is the best comedy show of the last decade, easily). Each "adventure" is about fifteen minutes long, each containing a thematically-linked live song. The whole kit-and-kaboodle is bracketed by appearances by Jack & Kyle speaking as hosts directly to the TV audience, as Burns & Allen and Abbott & Costello used to do on their shows. All in all, the total effect is as if "The Abbott & Costello Show" has been updated for the '90s starring Tenacious D and adding music. Did I mention, it was really funny?