"If you keep 불어, it will be 식어"

My wife overheard our son say this to our daughter during dinner, and thought it was funny -- "if you keep [blowing], it will be [cool]."

Today she caught me doing the same thing. P has picked up a tangerine after he'd brushed his teeth, and I said, "Put the 귤 down." I didn't even realize what I'd said until after she laughed.