When customer's come through my line at wal-mart, put all the items on the belt in a jumbled unorganized mess, but still expect me to bag their items in an organized fashion (Meaning, boxes only go with boxes, cans only go with cans, frozen with frozen... You get it). I normally try to bag the items like that anyway, because it just makes more sense. However, I don't want to have to reach all over the damn belt just to get it done. So if you have 3 boxes and 3 cans on one end of the belt, and 3 boxes and 3 cans on the other end of the belt... Guess what. Your boxes and cans are going in a bag together.
Customer's who bring a ton of stuff up to the belt, end up not having enough money to buy it all, then decide that they'll "put back" (By put back, I of course mean hand me) items that we have to claims out and throw away (Like frozen items, or produce, or bakery goods... If you hand us those items, they have to be thrown away because we don't know how long the frozen items were out of the freezer and we don't know what you could have done to the produce or bakery good (Possible poisoning)). I don't care if you want to "put back" a can of beans or a box of macaroni because that can all go back out on the shelf... But when you put back a gallon of milk, some cheese, some meat, and a few other frozen items instead of that $20 movie that you just HAVE to have... That just pisses me off.
Oh, and people who eat loudly or with their mouth open... That makes me want to punch people right there.