Claimed to be from "computer security" and that my computer was refusing to install security updates. I was passed from the bottom-tier caller up to a higher-level guy who would (they hoped) install the malware. Got a run-around about trying to make sure that I was the computer owner, and they got confused when I told them that I owned it but my grandson set it up. Over and over on that point... I thought of letting the guy try to talk me through "fixing" a Linux virtual machine but got tired of talking to vermin. This was the second time today that they called; the first time, they didn't reply when I picked up the phone.
Same story as Evan with a few extra details... they correctly guessed I use Macs, they said they were from URE Security, they navigated me to a LogMeIn screen where they would presumably install software on my machine, once I connected. Come to think of it, I should have gotten their 6 digit support code and reported it to LogMeIn. But I hung up and they didn't call back.