Oh dear, I am going to sound like AA Gill, (although nowhere near as pretentious obviously, or well educated for that matter).
If there is one thing that makes my blood boil in a restaurant it is when they try to get two tips out of me. We’ve all seen the drill, you get a long bill with a very discreet line at the bottom adding 10% or 12.5% service. Then you get presented with the Chip and PIN terminal where the waiter invites you to “add a service charge”.
This is what happened to me when I visited Livebait in Manchester.