Noun/Verb - Signifyin' is a form of street poetry used in the African-American community. Using a rhyme structure, it often contains a series of taunts or boasts. Soemtimes called "playin' the dozens".
As spoken by Rudy Ray Moore (aka Dolemite):
The Signifyin' Monkey
Way down in the jungle deep,
The bad ass lion stepped on the signifyin monkey's feet.
The monkey said, "Muthafucka, can't you see?
Why, you standin on my goddamn feet!"