I've had the barging up the queue behind me a few times, and it has always been a couple (maybe they egg each other on...?). But they always stop at me, and I've always put it down to the fact that I'm 6'7" and bouncer-like. The funniest one was last year when they were huffing and puffing behind me when I heard in a comedy whisper, "But he's wearing gym shoes Stephen!"