Cat siren

a fireman was cleaning the fire engine one day when he noticed a little girl across the street. she was busy cleaning her little red wagon which was fixed to look like a fire engine, ladder and all. the fireman walked across the street to admire the wagon. as he came close he noticed the power source was a large dog with a rope around his neck. he also noticed a cat with a string tied around its balls. the fireman thought this strange, so he said to the little girl,” would not it be better to tie that string around the cats neck?”. the little girl replied, “well that would be stupid, because what would i use for a siren?”.