Pressroom Slang

In pressrooms around the world many terms are used for everyday items found only in a pressroom as well as terms for doing certain things.

Can anyone tell me where or how the word SAP came from? This term refers to having a drink of alcohol, and can be used as follows. Lets go out for a sap at lunch.

Drinking before and during work is no longer allowed, but back in the day, many of us drank at work daily.