When you get to the lower floors in the I-SDF base, interrogate a guard. Sam will ask him about his LTL (less-than-lethal) weapon. The guard will tell Sam that the ammunition is some kind of electric round. Sam asks where he can find some. To this the guard replies: "It's not like you can shake me, and make my ammo drop on the floor". This is a reference to the Metal Gear Solid games, in which you can do just that.