Something bad that happens to someone as a direct result of them being stoned. This bad thing is usually something small and would most likely not have happened otherwise.
Person 1: Dude, that bowl last night hit me really hard. I almost dropped all my Captain Crunch on the carpet.
Person 2: Dude... your parent would have been so mad if you spilled milk all over their new carpet.
Person 1: I know, I just avoided a stoner tragedy.