One day a mechanic was working on car’s engine, he sees a famous cardiac surgeon walking by. Immediately he wishes the surgeon and invites him to his workshop.

The surgeon feels like humoring the chap so he walks into his workshop and is looking around.

The mechanic being a witty fellow offers the surgeon some coffee and then invites the surgeon to have a look of the insides of an engine and asks the surgeon:-

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Doctor you see this is the heart of a vehicle; I have just split it open, over-hauled it and have even changed 2 valves. This I would say is equal to a heart surgery. But sadly we mechanics get paid peanuts for the job when you doctors charge a ransom for the same work on a human heart. How unjust! (He sighs)

The surgeon a witty fellow himself, one who still has his humor tooth intact smiles at the mechanic and replies: – my dear man, try the same when the engine is running, and takes leave.