A goober left his car out in a hail storm.  When the storm was over he checked the car and found out it was covered with small dents.  He went to the local garage and inquired how to fix the problem.  The mechanic told him to blow on the tailpipe and the dents would be removed.

He took the car home parked it and proceeded to blow on the pipe.

Another goober came by and inquired what he was doing.  He told her she was blowing on the tailpipe to remove the dents.

The other goober responded, "That's not going to work unless you roll up the windows!"