Duke Nukem Forever

You'll need the Impregnator gun for this trophy. This gun has ammo regeneration similar to the Freeze Gun found in the original game, but be careful with it as it can harm you if you shoot the floor or wall you're standing on or next to. You'll first get this gun during the "Me, Myself, and I", where you'll be place into arena matches against Duke Clones and aliens. On the third level of the arena matches, you'll get the Impregnator weapon against alien Impregnators. You can unlock the trophy here if you wish by spraying at them, but it's much easier to wait until the floor section opens up. Crawl through the floor passage tunnels and into the vent and turn right, melee open the vent cover and drop down into the room filled with Duke Clones. Spray them all down and you'll unlock the trophy.