Oh, I hate people that do this. I have gotten a few cat butt faces by turning completely around and standing in line while facing them, then moving up as the line moves. For some reason, they don't do it when you're facing them.
Hand on hip & turned towards them works wonders, especially if you have extra sharp elbows like I do!
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Waiting is good. It means you're not going to die. The person you need to feel sorry for is the one who gets rushed into A&E and treated first.
I just try to stick a cart between me and people like that. Since I seldom go shopping alone, if I can not get the cart there, my Guy will turn himself into a human shield so people don't get too close.