A sexual position, usually a tight squeeze (if your with a woman) but if you manipulate the vaginal organs (usually the clitoris because it's the most sexual stimulant on a woman's body) then the anus, or
asshole, will open up like an umbrella do to the manipulation of the
vagina and relaxiation of the woman. That's when you sneak
one inbewteen the cheekys my fellow brothers.
With some tedious finger and licking action to my girl's pussy, her ass opened up faster than an umbrella on a down
poor but closed
like a bank's vault when I inserted my purple helmet
warrior. She no longer wanted anal after that.