A person who has sex, then instead of leaving through the front door, leaves through the back only to walk through the brush, trees and wilderness behind the house never to be seen again. Typically done after getting caught, or about to get caught having sex, or an orgy. Usually they are in such a rush to get the hell out of there, they put on whatever clothes they can just so they have something to wear.
There he goes sweetie. There goes fuckquatch, through the underbrush. Look at that, a rare sighting of that cryptozoological marvel. Honey get your camera and take a blurry picture of fuckquatch. Oh fuckquatch, what secrets do you hide?