The Shitty Dollar Trick occurs when an individual smears fecal matter (in this case, human fecal matter) on one side of a dollar bill. This dollar bill is then places on the ground, shitty-side down. An unsuspecting passer-by then picks up the shitty dollar and learns the definition of an unpleasant surprise. Distasteful? Probably.
"We just pulled the Shitty Dollar Trick on Dave's Great Grandmother!"