A firefighter is working on the engine outside the station when he notices a little girl next door in a little red wagon with little ladders hung off the sides and a garden hose tightly coiled in the middle.  The girl is wearing a firefighter's helmet. The wagon is being pulled by her dog and her cat. The fire fighter walks over to take a closer look.

"That sure is a nice fire truck," the fire fighter says with admiration.

"Thanks," the little girl says.

The firefighter looks a little closer and notices the girl has tied the wagon to her dog's collar and to the cat's testicles.

"Little Partner," the firefighter says, "I  don't want to tell you how to run your rig, but if you were to tie that rope around the cat's collar, I think you could go faster."

The little girl replies thoughtfully, "You're probably right, but then I wouldn't have a siren."