When your neighbors house catches fire, and all you can think of as you watch the fire department try to extinguish the blaze is that if it happened to you, at least all your games would still be available on Steam..
When you are cleaning up the next morning after a party...
and you catch yourself staring a little bit too long at a couple of bottlecaps in a pile on the table, feeling like you don't want to throw them away.
... Guess I've been gaming too much. We actually have a large collection of bottlecaps at our house, and have everyone put their caps in a container at parties...
When your PC desk is covered with dirty dishes and soda cans. Then the mess gets cleaned then a week later its filled with dirty dishes and soda cans again.
Or when http://www.youtube.com/watch?v=pt6e_MiUkms happens to your brain.