I'd take something resembling a stick and stick it in her ass crack.
But when this happened on my watch I had just told her "nice ass crack" and laughed.
She got ashamed and pulled her pants up.
Sometimes shaming still works.
When I see bitches with these "modern" torn jeans with holes in em, I keep pointing out "Listen, there is a hole in your pants. You might want to get it fixed." .
On some of them it dawns that they are embarrassing themselves, but some get angry over it.