Your equipment costs more than your car.
You often lay on the ground (in public) to get a different perspective (in the middle of the sidewalk or street).
^ You no longer even acknowledge the weird looks you receive.
You have gotten wet trying to get a particular shot.
You have risked your life or hurt yourself trying to get a particular shot.
You have been stopped by the police/security/paranoid citizen for shooting.
You have been prosecuted for trespassing because "it looked better from over there."
You have the photo/video page on craigslist in your quicklinks.
You own more cameras than pairs of shoes.
You've dropped a piece of equipment that is more expensive than the sum of what is in your bank account.
^ You're still paying for that particular incident.
You have access to a camera 90% of the time.
^ You curse yourself during the other 10%.
You have pulled your car over more than once to get a shot when driving only a few miles away.
You have a tan line from the camera strap.
You've sold your services or a print to someone you are not related to/best friends with.
You are able to manually focus and shoot without dropping your cigarette - ~dehk
90% of the time, you remember to take your lens cap off - ~dehk
You've defrosted your battery in the car's defrost before because it got so cold in the winter that the battery wouldn't work - ~dehk
You use your household vacuum to clean your sensor! - ~dehk
You have multiple packets of silica gel in your camera bag...and you live in Colorado...
You've gotten on top of your car to gain a little extra height for a shot - *HaikuKitty
You curse and swear when people walk into the scene when you're just about to shoot, especially a nice landscape - =Timothy-Sim
When your friends are tired of getting their picture taken for portrait shots - ~raven2007
It's when even your mother starts limiting how much you spend just to buy camera equipment. And you're an adult already! - =Timothy-Sim
You will travel 3 hours to grab 'the perfect shot' and not think twice about it - =SeptSky
When you're shooting wildlife and suddenly the animals don't even care your around anymore - =htdcam81
If you can wear out the eye cap on your viewfinder - ~dehk

If you have any, send them in and I'll post them!