A situation in which a person will say or dosomething not meant to be heard/seen by others. However, during said moment, a person not meant to have heard/seen (i.e. a teacher or someone of authority) will notice the action, usually by being within close proximity
Stupid Person's Definition:
A person says or does something stupid by a teacher
Hey, Courtney, did you see what happened the other day? I took this rancid nasty jizzed-up condom and slapped Zack in the eye with it!
Oh, darn! *slaps knee* I just had a bona-fide James Moment!