A senior citizen was showing off a new car he had bought to his grandson.

"Let's go for a spin," he told the youngster.

The old man pulled out of his driveway and placed his fingers above the top of the steering wheel, controlling it only with his thumbs pressed against the lower edge of the wheel.

"That's weird," the grandpa said, "I still don't hear anything."

"What are you talking about?" the grandson asked.

"The car salesman said I could hear lots of different kinds of music if I used a thumb drive."