It was invented not as a joke but because a schoolboy in Stonehaven dared a friend to eat a battered chocolate bar for lunch — and the chip shop said yes.
A whole Mars bar is chilled, dipped in the same batter used for haddock, and deep-fried until the chocolate inside turns molten and the batter crisps up gold. It's sold in paper straight from the fryer at chip shops up and down Scotland's east coast, usually with a fork stuck in the top.