When a person wearing a hoodie is uppercutted in the hood from behind. The resulting inside out hood is flattened, thereby looking like a "shark fin"
by K Stizzokes December 09, 2008
To uppercut someone wearing a hoodie from behind, causing the hood to turn inside out. The resulting "fin" is flattened, and stood up straight.
by K Stizzokes December 12, 2006