Car Stopped at Traffic Lights

This story was told by a priest who gave a retreat in the seminary when I was a seminarian.  We shouldn't be always knocking others down.  A car stopped at the red traffic light but when the light turned green the car was unable to move.  The driver got out to try to fix his car.  The driver in the car behind started to hoot his horn.  The driver of the first car went back and said to him, "If you fix my car I promise I will hoot your horn!"