Define Never Leave A Man Behind Meaning

Never Leave A Man Behind
When someone starts drinking a drink and doesnt finish it. this is said to remind them to finish it.
started by Gabby's friend Bob's brother. Nobody actually says it, but Gabby seems to think so.

Bob: well im done with this drink.
Gabby: its not finished... NEVER LEAVE A MAN BEHIND! ahahahahahah! im funny,
Bob: shut up you fucking mexican.
By Rhonda