When you stick your dick or a similar object into your partner/hooker's asshole, then you have them shit on said object while still holding it in as tightly as possible. This should cause the poop to go around the object and forcibly eject out the anus. The end result looks like a pressure washer spraying poop. DO NOT get in the way of this 'pressure washer,' it will inflict physical harm.
Note: Laxatives help to provide the consistency needed for the poop to flow like water.
Danny: Oh yeah John! Just a little deeper and then I'll pressure wash that silly grin off your face!
John: Yea! Pressure wash me all day! UNNGGHHH (orgasm) (poosplosion)
When someone, normally male, uses urine to clean "skid marks" off the inside of a toliet. This works especially well if done within the next 10-15 minutes. Works best as an unspoken agreement between roomates/partygoers.
"Hey man, I just took a wicked dump in your bathroom. Haha, left skidmarks all over the toilet."
"O great, next person to piss make sure to pressure wash that crap off."
Occurs when one (usually male) aims for the brown stains left from a previous user in a public restroom, in order to avoid misplaced blame for having made them.
Bro, I totally had to pressure wash the porcelain in that bathroom. There was a hottie waiting in line behind me.