I thought of another one.
People never examine the maps they are playing too closely, so any game with sufficient greenery, ghillie suits, or a prone button make for lots of fun hiding spots. (lookin at you CoD4)
BTW, lying prone WILL get you shot in the head more easily, but if you can find a place where youre inside a bush or lying in grass, you might as well be invisible. you can also substitute grass for your fallen comrades so long as a grenade doesnt flush you out. Trust me there is nothing more funny than lying prone in the grass next to the HQ(s) in headquarters or domination and hearing the other team yell "WTF? my game is broken!" or "theres lag or watever" afterward and knowing that you screwed them over.