There was a man who decided to ride his 10-speed bike from Phoenix to the Grand Canyon.  He made it across the desert with no problem, but when he reached the mountains, the steep grade wore him down.  Realizing he can't continue, he decides to hitchhike.  Two hours go by and not a single car has stopped.  A guy driving a Corvette stops and asks if he can help.  The bicyclist says "I could use a ride."  The driver looks at the bicycle.  "That won't fit in the car," he muses.  He opens his trunk and takes out a piece of rope.  He ties one end to the bicycle and the other end to his bumper.  "You have a horn on your bike.  If I go too fast, honk your horn and I will slow down."

This scheme worked well for several miles.  Suddenly, a Vette blows past them.  Not to be outdone, the first Vette driver takes off in pursuit.  They fly through a speed zone.  The patrol officer looks at his radar gun.  It indicates both Vettes are going over 120 mph.  He radios the officer ahead and says, "You've got two Corvettes headed your way.  They're both doing over 120 mph."  He hesitates a moment, then adds, "You're not going to believe this.  But there's a guy on a bicycle.  He's also doing over 120 mph and he's honking to pass..."