Pro-pain Trophy in Uncharted 3: Drake's Deception

Propane and Acetylene tanks can be shot to create an explosion which is capable of killing any unfortunate goons standing nearby. See below for a brief description of what they look like.

The best place for this is Chapter 5 - London Underground, towards the end of the level. You, Sully and Cutter will advance through the underground system to a point which you will enter an underground platform area with a train on the tracks. This place has a few propane tanks which you can shoot out near bad guys to cause an environmental death. For any bad guys that are taking cover or are too far away, go grab one of the propane tanks by pressing to pick it up close to one of them then throw it using much like a grenade. Now tap at the precise moment it passes them to shoot it and have it blow up taking out any hostiles in the vicinity. You may not quite tally a full 10 in this part alone but soon after it you will ascend some stairs, clear out some bad guys, advance on some dudes behind bars with red dot scopes that will retreat before you can kill them. Up this next flight of stairs is the end of the level but as you get to the top, grab the propane tank on the floor and turn around the way you came. 2 bad guys will be running up the stairs to catch you, simply throw the tank at them and shoot it for 2 easy propane kills, then hit restart checkpoint and repeat until you have the kills you need.