When an adult flips out, behaviorly speaking, over something relatively insignificant.
An adult tantrum.
The stewardess just told Jon our flight was going to arrive 1 minute later than scheduled. Now he's throwing his peanuts at her and cussing up a storm. He always throws a noreltny like this for the smallest things. I hope the Air Marshalls don't bust a cap in his ass for being "that guy."