In splitscreen select oddball and have starter as plasma pistol and no weapon on map and no secondary.Charge up plasma pistol to full and hold X while running towards the odd ball and the second you're supposed to pick it up, back away and if done properly you shouldn't have a gun.When in "no gun mode" spartans may throw grenades at any time, but elites may only throw them when riding in a warthog.dont run into a gun you lost or you'll pick it up and you'll have to repeat the process.If you pick up the skull, hold R while walking backwards. You should lose it. Have fun.