#3 just happened to me tonight..... Some a-hole hipster decided that he was going to go into the 10-items-or-less line and take 30 different items with him. I was about to say something, when the hero behind me walked around and just shoved the hipster's crap off the little conveyor belt. The hipster didn't say anything, he just walked out leaving all the stuff there.
The cashier lady didn't miss a beat and hit the 'cancel transaction' button then looked at me and said, "You're up, Hon."
I bought the guy behind me a pack of smokes he mumbled about getting.