When you are fucking a girl from behind, grab an electric hair trimmer to remove a square inch patch on the back of her head. Once you've reached climax, bust your load onto the hairless patch and glue the hair back on.
Mike - "I got fucking shitfaced and accidentally gave my girlfriend the toupee"
Joe - "Dude I toupeed the piss out of this chick at a party the other night"
A hair piece that is worn on the head, usually used by elderly men to hide bald spots. Can be used by unfortunate women for the same reason, or for theatrical purposes.