Quote from Kripke in the episode Spoiler: Corn is Delicious
Denise: What kind of universe is this? Kripke: I don't think we made it to another universe. I think we're stuck between universes. Denise: What exists between universes? Kripke: Best guess? Sort of an interdimensional taint? Think of it like being stuck between the balls of one universe and the asshole of another. Denise: You're disgusting!