From Halopedia, the Halo wiki
Were you looking for the Stick It Medal?
Stick It is an achievement in Halo 2 (Windows Vista). It is worth 5 Gamerpoints and is earned when you stick an opponent with a Anskum-pattern plasma grenade and blow them up.
It is represented by a golden 16-pointed star, covered by a smaller blue star, and a Plasma Grenade on top.