when leaving Walmart

Its stupid to but I always have because usually when im leaving the store, im either on the phone or im in my zone and so they catch me off guard. But They've only asked to see my receipt if I didnt put something in the bag. Regardless what it is, even for a big bucket of cat litter. But i've always showed them my receipt for just in case if I accidentally left something in the cart I didnt pay for. It happens. It hasnt happened to me yet but I feel like it might one of these days when im super exhausted