Actually, the episode I was referring to was "Cancelled" which was the "rerun" of the first episode, where they had deja-vu and the show "Earth" got cancelled, and the aliens were going to destroy the earth. Check it out, it was hilarious.
There was an alien that took the shape of a taco that pooped ice cream! haha!
Oh. My. God. There may be an episode I haven't seen?