1 definition by Isaac Fisher
Used in the binge-drinking themed sport of Beer Pong. While the game of beer pong requires that a ping pong ball be thrown from opposite ends of a table into solo drinking cups filled to a level with domestic beer; throwing a "Dirty Ball" is to toss a ping pong ball without rinsing it in the designated "water cup" with the intent of fouling the opponents domestic beer filled cup without their knowledge.
by Isaac Fisher May 21, 2006