Uncle Grandpa is only one of the amazing, relatively fucked up shows that Adult Swim provides the world. It's fantastic, and in a recent episode it got even more fantastic with the addition of The Melvins' Buzz Osbourne and Dale Crover. The due are summoned from… aliens and the void, I think, to help one of the little girl characters in the show form a band in place of her old, currently absent band.
It's worth noting that Osbourne and Crover both voiced themselves in the show!
