used to describe the brown marks in unwashed tightey whiteys belonging to someone who just couldnt hold it. or, alternatively, they had an all day wedgie.
Dude! Check out those skid marks! Dad must've had Mexican for lunch today.
1. burnt rubber marks left on tarmac when peeling out with a fast, powerful car
2. poo stains left on underwear when ass is not properly wiped hershey highway
1. That porsche left skid marks on the road.
2. I was taking a shower and noticed skid marks on my underwear.