There is a segment that do, rarely, where they discuss celebrity buttholes accidentally exposed in movies or TV. It's interesting because they're right about this being a completely taboo part of the body you really don't see, particularly celebs who might otherwise shows tits, bush, or cock.
The first was Anne Heche's from the Psycho remake:
It gave us this great song:
The latest episode question whether Aubrey Plaza showed off her brown eye in this scene from Legion:
The "official ruling" was no.
They did see someone else's, but not many, maybe 1 or 2 more. When I remember, I'll dig up the pics unless it's a guy. Cake will have to google that stuff on his own.