that you can throw a grenade into the stairwell in the building next to Arnhem Bridge (from the bridge through 1st floor window) on Market Garden to kill any campers?
that some people play in quiet rooms with their audio volume quite high - they can hear footsteps coming up behind them, they can hear the sound of expacks dropping next to their tanks, they can hear your glitching Tommy gun when you've picked up an enemy's.
that if you are within a certain distance and happen to move your crosshairs over an enemy who is the other side of a wall, their nametag will appear letting you "know" they are there.
that if you run everywhere in a straight line, a sniper can headshot you almost as easily as if you were stationary.
that players leave when they're no longer enjoying the game. Be mindful when you're in the enemy's main killing the same players over and over and over.