To 'Crotch Out' or 'Crotching Out' is when a female sits or slouches in an unladylike fashion (often for comfort reasons), with her legs akimbo and her crotch or vagina facing outwards.
It is more frequently seen on sofas, and in the presence of close friends/other females.
It is occasionally used as a mating display.
I'm just going to crotch out on this chair.
Look at her, crotching out over there.