When standing in line, do not stand directly behind the person in front of you. And when I say directly behind I mean three inches from their left shoulder. It's just creepy.

When you stand behind right behind someone, you're invading that "personal bubble" they have staked while standing in line. If you trepass that security boundary, I will not hold the person in front of you responsible if they go ape shit on your ass. Your problem, not mine.

Now this is where what I call the "Personal Bubble Effect" comes in. If you decide to stand too close to someone, they will in turn try to avoid you by stepping forward, ever so closer to the person in front of them, thus decreasing their personal bubble they claimed. This in essence turns into the Domino effect. It eventually reaches the front of the line, where the person in the front is squished into the counter.

Also, don't get too comfy with the people in line with you. They don't know you, and probably don't want to.

I was once standing in line, when I noticed a man in front of me. He had a shirt that bore the iconic Pep Boys on the front. When I was younger, I grew up near a Pep Boys store and seeing that shirt reminded me of that time. I mentioned the shirt, which he had not the slightest clue as to who the Pep Boys were and why I was notioning towards it. Suffice to say that would have been the end of the conversation, but the man continued on for 10 minutes about some complete bullshit about his life that I ignored.

Moral of the story, don't stand to close, or even talk to your neighbors in line.