A potato chip that is folded in half. Traditionally, one would make a wish while eating the folded chip, and the wish would be granted.

When you eat dirt for the first time and leave your family to build a shack in the woods

A wish chip is typically a chip that is folded in half in someway. However some also include 'bubble' chips (those with pockets of air in them) as wish chips. There is a certain way a wish chip must be eaten otherwise the wish is voided; for instance the chip cannot be touched by the thumb and must be picked up between the 'wish fingers' (the middle and index fingers.). Additionally there is some debate as to the process of actually eating the chip; Some rule that the single wish chip must be eaten and swallowed without opening the mouth or alternatively the wish whip must be crushed against the roof of the mouth with the tongue. Overall eating a wish chip in the correct way grants the consumer one wish per chip, that is proven to be highly unlikely to come true.