when you sign all your personal checks with your WONID. 
when you strafe supermarket aisles. 
when you visit a place and say to yourself "This would make an awesome map." 
when you are on IRC saying, "yI love playing CS!" 
when your wife left you, your kids have left you, but you don't give a shit because you just knifed someone and you have an awesome kill ratio.
when you are nervous at work becuase there is an air conditioning vent above you.
when you stop masturbating becuause you think your neighbor has a wallhack. 
when you ask a supermarket employee where the buy zone is.
when you pick out your clothes based on what blends the best. 
when every time you sit at a computer you automaticlly put your fingers on A,W,D and the space bar. 
when you get up 2 hours early for work so you can play, but it doesnt matter because you're late anyway. 
when you sneak up behind your friends and start stabbing them with with index finger while make knifing noises. 
when someone beats you in something and you yell "HAX!" 
when you call in sick because you lost your match last night.
when you carry a knife to school just so you'll get there faster.
when you get a glock and shoot someone in the head expecting them to live.
when you write an english report in 1337. "1t w4s t3h b3st 0f t1m3s, 1t w4s t3h w0rst 0f t1m3s..."
when you get beat on a console game and think the other person is wallhacking, even though they are sitting next to you.
when you switch between your pen and your pencil constantly, to be more like HeatoN.
when you're going for a job interview and your first words are "Can I join your clan?"
when you try to defuse your alarm clock in the morning.
when you wake up and get angry that you didnt spawn with 800 dollars.
when you ask the school bully for a scrim.
when you crouch for more accuracy while playing dodgeball.
when you ask for a restart after missing the school bus.
when you're playing a sport and the opponent talks to you and you say "TEAM TALK ONLY PLEASE."
when you watch a movie and are constantly telling your friends/family what kind of guns they're using and which ones are better. 
when you try to carry something up a ladder backwards and wonder why its not working. 
when on a cyber-network you ask for: "1v1 \ my bed \ east \ pm me" and "NO pugs!" 
when before sex you say "DR" and "lo3."
when you call the american army "lame" because of HE-spamming.
when you ask a friend to crouch to help you climb a small crate.
when you are getting a midnight snack and try to bunnyhop to the fridge in an attempt to make less noise.
when you join the army and lose an arm from the belief that that grenades explode three seconds after you throw them, regardless of when you pull the pin.
when you curse Valve every time something goes wrong in your daily life.
when you ask what "sv_gravity" is set at when playing basketball.
when you accuse someone of stealing your kill in a shootout.