In bunker 2 in the begining, after killing the guard, go to the right into the area that seems usless. Use your watch magnet extract and aim it down. Use it and you will get knives. Also, next to the camera room with the cv tape, in bunker 2, go through the door to the right. Throw knives up into the air and hear them go up and come back down. This is also helpfull when you are being chased. Throw alot of knives in this area when being chased (by people in multi-player or the game) and the knives will land on the heads of the people chaising you. This will happen everywhere as long as there is alot of space above you, but you have more controll in bunker 2.