Tourists walk up to busy bar, guy stood in doorway talking to waiter/waitress comes over and greets them and takes them to an empty table outside. Takes their drinks order, comes back with drinks, then with the bill. A short time after they pay a waiter/waitress appears with another bill.
The guy stood talking to the waiter/waitress had been telling them that he is waiting for some people he works with/met earlier/is driving round. He's already arranged for a table to be held. Once the right number of tourists arrive for the table he goes over and greets them, takes their order and goes with it to the bar, he then brings their drinks and gets their bill (he's told the barman the same story while waiting for the drinks). He then waits for the payment and walks off out another entrance, away from the tourists with the free money he's just been given.
This happened to us last night, moral of the story, take your bill to the teller and pay there!