How Many People Have Wanted To Do This?

From The New York Daily News: A disabled Florida man got a beat down from an elderly wacko Walmart customer who freaked out after the wheelchair-bound man used the express checkout lane to purchase more than 20 items.
William Golladay, 77, whacked Walmart customer John Malherbe, 65, repeatedly with a shopping cart after Malherbe bought 22 — instead of the maximum 20 — items in the Punta Gorda store’s checkout aisle
The register rage started when Golladay began to count, out loud, the number of items Malherbe had to purchase as they waited in line, WZVN-TV reported.
“He kept screaming about too many groceries and stuff,” Malherbe told the station. “And I said, ‘What?’ I think it was the shock, of ‘What? Are you serious?’ And I kept asking my wife, ‘What?!’”
Read more: http://www.nydailynews.com/news/crime/senior-beat-man-checkout-items-cops-article-1.1581406#ixzz2qXRgEGy5
While I don't advocate beating someone for acting like a jerk, I have no problem shaming a person who is a rude shopper who thinks rules are for others and those who only think about themselves.
As a customer/cashier, nothing frustrates me more when the person in front of me takes several minutes trying to find 2 pennies so they get 3 extra coins back in change. 
Or the person who spends 5 minutes trying to find their credit card.
Or the person who brings 30 items to the check out line and puts back 20 of them because they over spent.
Or at the self check out registers and the people don't know how to use them.
Or people on cell phones or text when they are supposed to be checking out.
Or they get to the register and  they forgot an item and they insist that they run back and get the item while the entire line waits for them to come back.
So, I can see the guy in line getting pissed at the guy who had too many items in the check out line.  The guy thought the rules were for everyone else except him.