whats up with 86

a question for anyone with experience in restaurants. when an item is out of stock it is generally “86’d”. same deal with extras in gangster movies. " where’s Gino?" " the coppers 86’d him" why is 86 used here. and what about agent 86 on Get Smart? please help me with this frivolous yet annoying problem.

The Word Detective’s musings.

The American Heritage® Dictionary of the English Language

Don’t forget the master himself weighed in on this subject.

Where does the term “86” come from?