From Halopedia, the Halo wiki
Sticky Fingers is a spree medal awarded in Halo 3: ODST Firefight mode and Halo: Reach multiplayer, campaign and Firefight. In Halo 3: ODST it is awarded for sticking ten opponents in a row with a Plasma Grenade or Type-2 Antipersonnel Fragmentation Grenade without dying. In Halo: Reach the medal does not require kills to be consecutive, just that the player kill ten enemies with grenade sticks without dying.
It is represented by a bronze four-pointed star with a green-glowing blue orb in the center.