A fork of Rural Dictionary
When you are long in the balls and you wear a hole in your underwear creating a stamp or cookie cutter like impression.
Justie was so long in the junk his underwear always rocked a sack stamp
When you take a steaming dump in a pillow case (sack) and then smack an unknowing victim across the face leaving them utterly speechless.
Aaron was walking in from work when I surprised him with a Dirty Sack Stamp to the face.
The heart shaped sweatprint made by a mans hot, sweaty testicles on a chair or other hard surface. It may or may not be accompanied by an ass stamp.
When that dude left the sauna, he left a sack stamp behind.