A mechanic was removing a cylinder head from the engine of a Range Rover when he spotted a well-known heart surgeon in his shop.
The surgeon was there waiting for the service manager to come take a look at his Mercedes when the mechanic shouted across the garage: "Hey doc, can I ask you a question?"
The surgeon, a bit surprised, walked over to where the mechanic was working on the Range Rover. The mechanic straightened up, wiped his hands on a rag and asked: "So Doc, look at this engine. I open its heart, take the valves out, repair any damage, and then put them back in, and when I finish, it works just like new. So how come I get such a small salary and you get the really big money, when you and I are doing basically the same work?"
The surgeon paused, smiled and leaned over and whispered to the mechanic: "Try doing it with the engine running."
Hat tip: Babs of Beetle's Memories 'n' Ramblings