Three doctors were on their way to a convention...

Three doctors were on their way to a convention when their car had a flat.

They got out and examined the tire.

The first doctor said, "I think it's flat."

The second doctor examined it closely and said, "It sure looks flat."

The third doctor felt the tire and said, "It feels like it's flat."

All three nodded their heads in agreement. "We'd better run some tests."