What does that even mean?

I work with claims...some days happen without event, people know they owe bills, and business continues as usual. I have, however, encountered some really interesting name-calling and threats. All I can say is...What does this even mean? A few examples of things that make me worry for humanity:

-I'm going to come down there and cuss at you so hard, the police will have to get involved

-I'm going to sue you until the end of time

-I don't care if I'm responsible per some contract, you have no right to send me a bill

-Of course I signed the contract, but who reads those?

-It's your responsibility to tell me everything that I need to know before I rent a vehicle

-You're a lying, cheating, stealing *******, and **** (Reply: Sir, I don't work there, I'm at a claims office in....) * PAUSE* Oh, I'm sorry, I'm going to go talk to them (hangs up)

Sometimes, phone calls at work are synonymous with ***FACE PALM***, all day long.