Words that rhyme with Punkin'

I was driving Caedmon to soccer yesterday when Caedmon pipes up from the back seat:

C: I think there is a bad word that rhymes with punkin'...

Me: Really? Like what....chunkin'?

C: No, I think it is..... insert the f-bomb here

Me: {trying to contain my shock and who am I kidding...my laughter} Buddy, I don't think we should rhyme those kind of words. That is a very bad word...and while they do sound similar they don't actually rhyme.