Piñata

Piñata is a skull in Halo: Combat Evolved Anniversary and ''Halo 2: Anniversary. ''The Piñata Skull in Halo 2: Anniversary was a timed exclusive for pre-ordering the game;so, it has no location in the game.

Location (CEA)
This skull is located in the mission Two Betrayals.The skull is towards the end of the mission,you must complete enough of the mission until you spot two banshees.Then Cortana will tell you to fly to one of the towers,don't.Instead fly back through an earlier part of the mission where a large forerunner tunnel is.Land on top of the tunnel and look next to the small pillar,and the skull will be sitting there.

Piñata Skull location video here

Effects
The Piñata Skull's effect makes enemies always drop grenades when punched.This affects all types of enemies in the game.