... You make your own ice cubes.
My NJ grandsons are visiting this week, and they came to the house last night. My 7-year old GS asked for water so I got him a glass of tap water with ice cubes. I left the ice cube tray on the counter. He came in to get the water and picked up the ice cube tray and asked, "what's this?" Then it dawned on him, and he asked me incredulously, "You have to MAKE your own ice cubes?"
I didn't realize I had reached such a high level of radical simplicity!!