The act of defecating in public, usually on a wall or free standing object. The act differs from traditional public shitting given that the taker extends the torso away from the wall, leaving the legs unbent and the ass well above the head. The single most important characteristic of a wall shit is the pressing of the cheeks against the wall so as to ruin the wall and wipe in unison. A perfect wall shit rarely results in feces on the ground and is most commonly the result of a spurned attempt to use a public restroom. As such, it is an act of both outrage and necessity.
"Hey, did you see that Melvis in the Raiders starter jacket taking a wall shit on Blue Heron Blvd, that guy has no regard for property."
"There's Jeff George, former Raiders Quarterback, wall shitting behind the gas station, boy how the mighty have fallen. Never thought I would see the day where a former football star is reduced to taking a wall shit. What a loser."