I told a version of this in the Thread, "Guess what hppened:

Two nitwits go to a used car dealer with 500 dollars and want to buy a used car, The dealer says, "We con't have any 500 dollar cars, BUT, we hav ethis camel in the back lot who's trained to stop on red lights and go on green. You fill him up with water and a bale of hay, once a week, and your all set.
They buy the camel and away they go.
One week later the salesman runs into the two nitwits and asks, "How are you getting on with the camel." "Aw, we lost him", they reply. "How can you lose a camel?" asks the salesman.

"Well, like you said, he stopped at a red light and we heard someone say, "LOOK AT THE TWO ASSHOLES ON THE CAMEL." We got down to look and the light turned green"