Yello's delicate insides have been described as "surprisingly soft and tight" and entering her is like "sliding into soft, warm butter". A strange analogy for sure, but it gets the imagination going.
Note:
This is part of an (for me at least) experimental sketch, just showing a cropped scene, while still transporting all the necessary info for the audience. I think its even more intense, even if it does not show the action explicitly.