Phew... that really was a close one. Customer almost blew up on me when my boss was gone errand-running. He was shaking, almost unable to talk due to anger. Luckily, I was able to talk him down and direct him to another shop.
I know that there are people with anger issues I met them. A few actually at my school. Like I remember on last day one guy had less school skips than girl by 100 and he's like "100!!! Woo!!" and I was like show off so he hit me xD
But yea, you got lucky, hopefully you'll be lucky like that always