A "Clown Mask" is created when two men have a threesome with a woman and finish by ejaculating onto each others hands, high-fiving and then slapping the woman in the face simultaneously, after which one of them bops her on the nose. Giving the white-faced red-nosed appearance of a clown.

Having unprotected sex with a girl when shes on her period than removing your penis and rubbing it on her nose, creating a red nose like a clown would have.