What's Your Problem?

Sometimes, it takes everything in me not to yell at the top of my lung capacity, "WHAT'S YOUR PROBLEM?"  There was a guy yesterday who came up all grumpy wanting to exchange something.  He didn't want a refund, he just wanted to go get something else.  The second time he approached me, there was still nothing that could crack his surly demeanor.  He was crabbed! Okay, so I started to do the exchange, then he threw a fit and accused me of ripping holes in his precious plastic bag.  As he straightened his plastic bag, which I noticed had no holes, only a few wrinkles, I saw he didn't share my feelings on plastic bags.  When I see plastic bags, I think how they kill animals, fill our oceans and trees and  in my mind are one of the worst thing ever invented.  I diverge. Next, the man put the new item in the bag, the more expensive item which I hadn't scanned yet!  I  said nothing to him, as I gingerly pulled back the bag in order to expose the barcode, hoping I didn' set off his simmering temper which was apparent in his body language.  I'm the first to admit I have my own issues, but sometimes at work it's hard to realize that somebody else's issues are all his, and that if he pushes my buttons until I yell at him, which I've never done at work, then he's won the match of the psyches.  I know I'm way smater than this guy, and I am not going to let him win, because he is annoying as hell.