For judokas mostly:
-you think learning to fall helps you learn to throw people.
-you see someone taking a bad fall off his bike, and the first word that pops into your head is "ippon!"
-every time you see a big open space you have to restrain yourself from doing ukemi for no apparent reason.
-when you see some big guy walking down the street you plan how to throw him on his back and then armlock him.
-you secretely wish that some untrained, unarmed, and unaccompanied robber would come and attempt to rob you.
-your girlfriend thinks you're a freak because you have callouses on the back of your fingers from doing judo grips.
-you instinctively bridge and roll whenever you wake up from a nightmare.
-you're teaching your kid to ride a bike and start off with ukemi drills!
-you get into bed with a forward roll.
-a shirtless attacker becomes your worst nightmare.
-you choose your dates by how well they look in a Judogi.
-you spend more time on top of your friends than your girlfriend.
-you say "you should see this new technique I learned" and all of a sudden you're the only one in the room.
-you keep having this dream about your mother-in-law reversing your best choke.
-your dog shakes hands with everyone but you.

-when you are sawing wood or hammering nails you consider it uchikomi.
-you can take your child to practice because you're in the same class.