Noun
(colloquial, humorous, euphemistic) A visible feces stain left on underpants, trousers, or sometimes the toilet bowl.
A long black mark left on a road surface from the sliding or skidding tires of a motor vehicle that has lost traction.
Any other mark or stain caused by one surface skidding along another.
The ladder that slipped left a skidmark across the tile floor.
The man had skidmarks on the knees of his jeans.