Being evil

Ok, at the store, someone parked next to my car and left about 10 inches between their car and mine.  So, when I came out, I climbed in the passenger side, got in the driver seat and thought.  I put my car in reverse, rolled back a bit and opened the door.  The result?  Well, let's just say the car that parked so fucked up had a flat front tire.  Hmm, how did that happen?