Oh, I know, my parents did it too. Still appalling though.

ETA: Mind, I'd discovered for myself by the age of five that ice cream on infected tonsils was acutely painful, so even had I had them out much younger I doubt they'd have tried that particular line on me. "You'll never have tonsillitis again" would have done nicely as a motivator, and in fact did. It was the doctors who wouldn't go for it.