When it comes to Walmart's self-checkout system, and I don't know if it's been mentioned yet or not, what makes me laugh is when you have items you don't want to bag, or can't, due to size. After you reach that limit of three it stops you from proceeding further until an attendant comes and resets it. And you usually have to flag them down. They say they do it to help prevent theft. Yeah, like I'm going to shove a 24 count carton of pop down my shorts.
And then there's the time factor between scanning and getting the item into one of those plastic bags (which are all stuck together) before you get the dreaded "PLEASE PLACE ITEM IN THE BAGGING AREA!!" Have you ever tried to get a 24 dbl roll pack of AngelSoft TP into one of those bags? LOL