As a former cashier (grocery store not walmart admittedly, but I doubt things are that different), I dont think weird uses for the items are the way to go, the cashier is barely even going to notice or care what you’re buying. what I bring to freak out the cashier, are some item that needs ID to buy, some big heavy item with the barcode removed so that it will take a bunch of lifting and turning in a hopeless effort to find it before someone eventually has to go find another one and bring it over, and a propane refill if walmart does those (at my grocery store the process to go find a full one was a pain, especially in the winter since they were outside). Further, I try to buy these items with the help of a ton of expired and unexpired coupons mixed together, several gift cards, and a stubborn half-deaf old person who wont take no for an answer.