I'm a what?

As I was getting ready to change Todd's poopy diaper, I remarked, "You're a smelly boy!"

Todd indignantly insisted: "I'm not a smelly boy!"... followed by a pause as he mulled it over and then said quizzically: "Smelly boy is what?" (his way of asking "what's a smelly boy?")

Apparently he didn't need to know the definition of "smelly" in order to deduce from my tone of voice, that it wasn't a compliment!