Why would you “put it in a glass case and throw sugar at it”?

Someone on the radio just read out a rude poem sent in by a listener about the show’s producer – then said he intended to put it in a glass case and throw sugar at it. Googling, I see this phrase used, but I can’t for the life of me work out what it means! What kinds of things would you do this to? Where does it come from? Enlighten me!