The act of shitting your pants and going in somebody's car. Also the shitty underwear should be thrown into a tree somewhere near the car. Also can be referred to as Sandflossin'
Dillon-"Why does my car smell like shit?"
Cody-"Cause I was Sandfossing in your car last night...Sorry. Just look up in that tree."
Dillon-"I guess them panties are a Dundatta."