When you ask the cashier for the total before they ring up the last item, so they will forget to scan it. Only works if you are purchasing 4 or more items, the cashier is not putting the items into a bag one at a time as they scan them (or you are skipping bagging altogether), and the last item doesn't have a beeper. Even then, it doesn't always work, but when it does, it feels oh so sweet, especially if the item they forget to scan is the most expensive one. The term is a play on the word shoplifting, combined with the name of the inventor, who is occasionally known as Schnappoulop.

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