That song is the Tits
It's by Yesca...Which to the best of my knowledge was the only song they ever did. I researched it some time back and saw that the guitarist was a studio musician that had tons of other material but that was the only song Yesca ever did
And the name of the song is Lost Due to Incompetence(Theme for a Big Green Van)
Yes I know that song is timeless
On a side note: the song version is different than what is played in Up in Smoke
Try Limewire~ It props up there from time to time