I was trying to think of a good clear way to word a new tag. Things like this would get it:
I'm thinking nose_to_anus maybe. Tends to show up just once in a while, usually in oral from behind type situations, but elsewhere sometimes too. To be clear, I'm talking about when one character's nose incidentally (although I think it'd be right to apply it when it's on purpose for sure too) bumps up against another one's anus (or I guess their own for flexible ones) while they're doing whatever they're doing. Or I guess it could be even looser and include when it's just right next to it, if not actually making contact.
Thoughts?
Updated