Grenade Stick
From Halopedia, the Halo wiki
Summary
The Stick It Medal is awarded for killing an opponent by sticking him with a Plasma Grenade. It is availible in all Multiplayer gametypes where Plasma Grenades are availible and has a Bungie difficulty rating of 3 (out of 10). It is represented by an active grenade on a 16-pointed star. After you stick and kill an opponent with a plasma gernade a message appears on your screen that says: "You stuck (player)".