This is a fetish known as 'cuckold cleanup'. Usually it involves a closet homosexual who gets off on pimpin his wife out to random strangers. Often the husband will sit in the corner and actually videotape as his significant other gets pounded by foreign cock. Once the creampie has been injected, it's like 'all you can eat' night at Red Lobster. Yum yum eat em up.
For centuries many will wonder - how did he do it? How did one man fit an entire basketball into his anus? Vigorous week-long training sessions? Nah. Optical illusion? Nope. Homosexual superpowers that transform one's rectum into a 4th dimension gateway? I suspect so.
This is from the 1976 classic Water Power. It's a lot like Taxi Driver, except this Travis Bickle has a little fetish for forcing woman into doing enemas at gun point. The film is actually based on real crimes committed by an Illinois man dubbed the "Enema Bandit". Anyway he's dead now, so R.I.P you scat-loving motherfucker.
Initially she makes it pretty clear that she doesn't want anything in her ass. But our hero Johnny Cock Rocket uses the powers of persuasion and before you know it he's making sweet love to her festering cornhole. Not exactly fap worthy but if you're like me you'll fap anyway.