Definition of skid marks:
(n) :
(colloquial, humorous, euphemistic) A visible feces stain left on underpants, trousers, or sometimes the toilet bowl.
(n) :
A black mark left on a road surface from the sliding or skidding tires of a motor vehicle that has lost traction.
(n) :
Any other mark or stain left on a surface from a sliding or rubbing object.
(n) :
(colloquial) A mark of a soiled finger wiped on a surface.
(n) :
Any burn on the skin caused by scraping the skin against a surface.