I did this on another forum before...
You know when you play too much (instert game here) when...
You stand on your roof top and wonder "I think I can jump from house to house"
You find places that would make a good place to camp and break out a sniper rifle.
You see crates and you want to bust them open with a crowbar.
You drive down a highway and see a sign "Campers ahead" and wish you had a grenade.
You wish you could strafe jump.
You see opertunities to use a rocket launcher in everyday life.
I've actually done some of these