Is it only me that seems to get stuck behind someone who has goods that do not scan properly, something that needs changing, dozens of coupons which invariably needs discussing with the cashier, can't find their clubcard, who is holding up the queue whilst waiting for their partner/friend to get a forgotten item, argues about the bill with the cashier instead of going to customer services, when the cashier buzzes for assistance she has to do it several times before someone come sauntering over? Once I was so infuriated by the last example after what seemed an age, that I left everything on the conveyor belt and walked out. It was not my usual supermarket so they would not have recognised me again.