Fractals of family life - films

An attempt to keep teenagers engaged with the conversation at the family dinner table, that did not go as planned.

Mother, "So what would your list of desert island films be then?"

Younger son, "That's really difficult, I can't think of any films that are set on a desert island"

Mother and elder son collapse in a heap of hysterical laughter ( and when recovered, all go to watch "Moon", not set on a desert island)