Call of Duty: Modern Warfare 2

I got this trophy without even trying, chances are you will too. During the 2nd mission 'Team Player' after the S.S.D.D mission, you have a grenade launcher attachment on a M4A1. Follow the on screen prompts to get the grenade launcher out and then look across the other side of the bridge, enemies in large groups will be shooting at you. Aim the grenade launcher crosshairs so the line at the bottom is sitting on the enemies. You have lots of grenade launcher ammo so just keep randomly firing the grenade launcher over the other side. You won't know you've killed 3 as it's too far away to see, but the trophy will pop once you do almost straight away. Video by Nextgentactics:

https://www.youtube.com/watch?v=GiIorxOrbeE