First, if you want the dog pissing on you.......don't hold your breath. Despite it's use as a comic device in film, that is distinctly un dog like behavior. Dogs piss on THINGS, to mark territory. They do NOT intentionally piss on whos because whos move, unlike trees and fire hydrants. See territory marking.
Second, Urine, inside the body, and AS it exits the body, is STERILE. It's the point where it makes contact with something outside the body where it becomes potentially contaminated.