When a man you may or may not have had a relationship with does his very best to mark you as his own with obvious gestures so another man knows you are "taken". Derived from the action of dogs pissing on hydrants, trees, appendages etc. to mark their territory and to signal to other dogs that "this territory is taken".
"Damn, Carrie, that Last Resort left a big ole' hickey on my neck and now I can't try to bang that hottie I was talking to last week!"
"Girl, that fucktard's always trying to piss on your leg! You must like it, you keep going back!"
"Why does your husband always put his arm around you when another guy says something meaningless to you? Does he always piss on your leg like that?"