When you penetrate an asshole and moments after you pull out, a small piece of shit flies out like a bat coming out of a cave. Think of the shit as the bat and the asshole as the cave... bats in a cave.

A reference term for when you have a booger in your nose that is clearly visibly from the outside.
This context is found in an episode of Sex and The City.

visible clumps of nose goblins, often found clinging to nasal hair.

An obvious booger in one's nostril.

When I was growing up: "Bats in the Cave" is when you spread a guy's shitter so you can buttfuck him but he's got a load of black dingleberries hangin' from his asshairs.

A description a woman may use for being celibate or not having had sex in some time.

u has boogers