A dude tried to short change me once. I told him I am going to do one thing at a time so if he had multiple requests on how he wanted his change it would have to wait. The look on my face as I said this to him as well as how I had the big bill he was trying to break made him realize he picked the wrong person. He shut the hell up, took his correctly counted change after I subtracted the amount he owed for his meal, and left with his tale tucked between his legs