ag·gro 
(
ăg
r
ō)
n. Chiefly British Slang 1. Aggressive or violent behavior.
2. Irritation or exasperation: "Postponing new hospitals and roads causes far less aggro than sacking town hall or Whitehall workers" (Economist).
adj. Slang 1. Aggressive or violent.
2. Daring and skillful, especially in a sport such as surfing.
[Short for AGGRAVATION and AGGRESSION.]