little Johnny went up to his mother and said
 
"can I play with the porcupine too mommy"

wherein mum says
 
"what porcupine, we havent got a porcupine, where did you get that nonsense from"

to which a very indignent young Johnny replied

"you have so, I heard you say to daddy that if he did the dishes tonight then you would give him a hedgehog"

Thanx Dave nice play on words LOL