Its when a group of little people (at least 4) dressed as monkeys are sent to kidnap a person, tie him or her up, draw penises all over him or her, piss on him or her, and crap in his or her mouth before walking away. Its named after a monkey in the famous show "Lancelot Link Secret Chimp".
While vacationing in California, my friend was the target of a Dirty Nance causing him to walk home from the beach smelling of urine and feces.
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