Bullets. Used in Call of Duty (and other shooters) cuz you pretty much have to go Rambo in single player to get anywhere, or the enemies just keep coming. Used in sense of automatic weapons, as that's pretty mush all Rambo used.
(Playing Co-Op Call of Duty 5)
Guy #1: Damn, I'm getting points like crazy!
Guy #2: Yo, move up! I'm almost out of Ramboes!