Tenacious D is, btw, Kyle Gas and Jack Black, or KG and JB as they refer to themselves in both real life and in the film.
(Spoilers)
The film follows JB from his ultra oppressive family and his father who is both Meatloaf, and an extreme Christian pastor, and wont let JB listen to his music, which really is his only escape. So JB hits the road, and many years later, still looks like his younger self, as he makes his way to Hollywood after seeing a vision. While in Hollywood, as a grown man, he runs in to KG, who we find out knows all the major performers, and has rocked out with the likes of The Who, Kiss, and Coleflatch. It turns out he hasn't and KG is the same low life that JB is. They both discover something while living together however, they both have a passion to rock.
KG and JB then find out something about a mysterious guitar pick from none other than Ben Stiller, in a hilarious cameo role. They must get this pick, or KG won't be able to pay his rent, and the duo will suck **** at the open mic performance they have to play.
So they set out on the road for the Rock Hall of Fame, which in this film, is in Seattle Washington. Along the way, they bump into Tim Robbins, who happens to be in search of the guitar pick, but due to a failed earlier attempt, can no longer walk with his broken legs.
The duo break into the Rock Hall of Fame and find the pick, only to set off a disaster but they manage to escape.
With the pick in hand, its time to conquer the show that they nearly miss. Will they make it, or will the devil stop them.
END SPOILERS
This film delivers what it promises, comedy, and most of it raunchy. We alreaedy know the language that is to be used in the film, its vulgar right, because this is Tenacious D right. I have no problems with the content or the language, its hilarious.
The film has a few moments were you wonder what happened to the script, but it picks (pun intended) itself up and finishes triumphantly. The story is hilarious, Jack Black and Kyle Gas are an inseperable pair, and this film scores high in my opinion. Its a great comedy, with a few flaws, but some awesome cameos and appearances by Tim Robbins and Ben Stiller, among others.
TD and the POD gets 3.2 stars out of 4 from me, nuff said.

Kyle Gas passes gas in a vision Jack Black has.