A hybrid of a power bottom and a bodybuilder; a guy who has a very muscular body and a slit like butthole that somewhat resembles a vagina in appearance due to extensive and frequent penetration by larger than average dicks, sex toys, and/or fists.

when you're hungover as shit after a spending a night drunk as a skunk

A vagina on a body of substantial muscle. Women bodybuilders, and especially female/trans persons on steroids, create the juxtaposition of masculinity and femininity. A pussy graduates to "muscle" status when it looks like it can put anything that gets close to it in a head lock.