Turok

This achievement must be unlocked in a "player" match, not a "private" match. First of all you need to be playing the second Co-op map "Shadowed Paths", and after you hack the terminal next to the rocket turret, you need to follow the path until you come across two raptors eating some dead meat. To the right of them is a stickygun so head over there and grab it, kill the two raptors and two dilos will come (one at a time), it takes two explosions from the stickygun to kill a dilo, one knocks it down and the second kills it. Once you successfully kill a dilo with the gun the achievement will unlock.