This little term has several, possibly related, meanings:
To refuse to serve an unwelcome customer at a bar or restaurant.
To throw away.
Indicating that an item is no longer available.
The term is American and originated in the restaurant trade. All the meanings loosely refer to something that was previously okay becoming not okay. The actual origin is uncertain but is likely to be one of these:
From Chumley's Bar and restaurant at 86 Bedford Street in Greenwich Village NYC.
A reference to article 86 of the New York state liquor code which defines when bar patrons should be refused service.
From Delmonico's Restaurant in New York City. Item number 86 on their menu, their house steak, was often unavailable during the restaurant's early years.