A ship engine failed and no one could fix it, so they brought in a guy with 40 years experience. He inspected the engine very carefully, top to bottom. After looking things over, the guy reached into his bag and pulled out a small hammer. He gently tapped something. Instantly, the engine burst back into life.

The engine was fixed!

Seven days later the owners got his bill for $10,000.

“What?!” the owners said. “You hardly did anything. Send us an itemized bill.”

The reply simply said: 
Tapping with a hammer: $2
Knowing where to tap: $9,998

One Liner

A fool and his money are never around when you need them.