I had a guy threaten to burn down the building my friend worked in and murder him because he didn't call him Mr (last name) once.

Had a guy threaten to beat me up because I told him the software he bought works fine, but his computer had a problem and needed to be fixed to make it work

Had someone throw a camera at a co-worker because it took grainy photos in low light conditions when set to auto (anyone who knows the most basic information about taking pictures will understand how stupid this is) and my coworker was explaining that. Guy thought my coworker was lying and the camera was broken

A laptop thrown at another co-worker because his warranty was expired and it would cost money to fix it

Had an at the time currently active well performing MMA fighter shout at a manager while pointing in his face and vaguely threatening to get violent "don't you ever talk to me like that, I will put you in your place, no one talks to me like that"

Had a customer physically bar an employee from leaving their home after performing work because they wanted more work done beyond what was discussed, scheduled and paid for. The employee had to get to other appointments, and the guy didn't want to schedule another appointment.

Had someone follow me into a parking lot, assault and batter me because I turned right on green (you read that correctly) if I hadn't turned right we would have had a head on collision. He was from New York visiting my state.

Had a co-worker threaten to fight me because I told him I said "hey, I'm running really behind and need to focus on my work right now, we'll have to talk about stuff later." . He later got fired for stealing credit cards

People are nuts. Some of them, anyway. Some of those nuts have guns.