When a Man has Crabs infesting his pubic hair. He then shave off his pubes and gets a blow job from a woman, then he ejaculates on to the womans forehead and be for she has a chance to wipe off the ejaculate the man rubs his crab infested pubes into the jizz on the womans forehead. Giving her a "Crab Crown" after she went down town.
"Dude I gave this chick a down town crab crown last night. She was to pissed to wipe it off before she left."