Kill 5 with one fragmentation grenade.

Awarded after killing 5 enemies with one grenade. A good place to get this is after you get out of the church and there is a grenade gun on the ground near the stairs. Wait for a bunch of the soldiers to come up the stairs at the same time. Another way to get it is to wait at the bottom of the stairs on the subway level and when a bunch of SWAT guys come down, throw them a little present