Anything between anything else is a sandwich. A pizza folded in half is a sandwich. A taco is a sandwich. A ravioli is a sandwich. The Earth is a sandwich. I think the only thing that isn't a sandwich is probably the universe, but that's only assuming it isn't rolled in on itself and is actually flat. Folks don't believe me but then they cut a baguette in the middle but not all the way through, put stuff in it, and call it a sub sandwich, so I'm not wrong.