Back in 2000 when Clinton was still president and Bush and Gore were just beginning to campaign against each other, some goofy person on the Yahoo messageboards told me that he was going to kill me and my family, then do the same for then-candidate Bush.
I assessed (correctly) that he was just a goofy person being stupid, so my only response was to tell him that I was laughing at him. But one of the other posters called the Secret Service.
It was 4 AM Sunday morning so he got their answering service. It took about 90 seconds for a live agent to call him back and take down information about the threat.