When ppl who stand next to you for extended periods of time run a serious risk of getting Kimuraed.
When you're anxious about your jiu jitsu instructional DVD arriving in the mail.
When you'd rather watch your jiu jitsu instructional DVD than go out to the movies with your girl friend.
When you join forums about jiu jitsu and participate in them daily.
When you grow to love/hate Ryan Hall. lol
When you go to class injured, even if it's just to watch.
When you meet someone you don't like and in your head imagine rolling in for a knee bar on them. Maybe even throwing in a nasty heel hook just to get your point across.
When you wear your jiu jitsu school's apparel to non jiu jitsu events.
When you roll at home, even if you don't have mats.
When you roll on grass, even if you're allergic to grass. (this sounds like I mean drugs, but I don't. lol)