Ah, yes. Must be careful of little boys. Is there something you can use to show him how he can "move air"?

A tissue moved away just a bit so that he can move with his just the air from his nose? So that he can puff and puff and puff to get the concept of blowing out? Maybe with a little treat incentive to get a miserable (sick) little boy to play when he is not in the mood for it?