This achievement is slightly harder than "Enraged Frag," but can easily be completed on Desert Strike level 3 after a few attempts. You will want to angle your shot upwards to strike the first guy inside the pillars. Once you have the angle/power down, strike him twice more in the head making him enraged. Be mindful to abort the explosion after it hits his head each time. Now, change the angle slightly and do the same method to hit the second guy 3 times, aborting each shot after it hits him as well. Now, land a grenade in between both of them as they both should be enraged, and you will kill them, giving you this achievement.