Large Dog

A man was walking on the sidewalk and noticed up ahead that Little Johnny was wearing a red fireman's hat and sitting in a red wagon. It appeared that the wagon was being pulled slowly by a large dog. When he got closer to the boy, he noticed that Johnny had a rope tied around the dog's testicles, which probably accounted for why the dog was walking so gingerly.

Smiling, he spoke to the little boy, "That's really a nice fire engine you have there, son. But I'll bet the dog would pull you faster if you tied that rope around his neck."

"Yeah," Johnny replied, "but then I wouldn't have a siren."