1) You ask yor friends for their hands so you can throw kotegaeshi (nicely of course
2) You look at a low wall or object and think "Can I front roll fall over that?"
3) Your friends come to your dojo to give you things because they never miss you there.
4) When you go to school your friends ask "Which black belt threw the crap out of you this time?"
5) Your friends have learned to run when you say "Hey, I learned a cool move at class!" (The most common for me
6) You see fights and think "Oooh, Iriminage would be good there"
7) The voice(s) inside your head tell you Aikido related information and sound an awful lot like sensei