|1.||Idaho Skid Mark|
When a man and woman are having intercourse in the missionary position and the woman loses bowel control. The incident goes unnoticed and results in one or more large fecal matter stains on the bedsheet.
Joey: "I don't know what happened. I drilled her like an oil rig but when she got up, there were poo streaks on the sheets!"
Einstein: "The fabled Idaho Skid Mark..."