When a lovely gentleman from across the sea calls me and says
"hello I am from the computer department, there seems to be a problem with your pc"

me:"what department is that again?"

Him:"The computer department"

me:"Could you also tell me what that loud samba music is in the background?"

I like to ask them about my operating system (often I'm told it's Apple Windows 7, 8, 10), then about how they managed to get through the hardware and software firewalls (apparently they can because they are the computer department). Finally, I tell them that the virus they can see is there deliberately, I am writing it to infect the whole internet, and that by connecting to my computer, their computer now has it, so I can access their files. Generally at that point the line goes dead...

I usually just play along until they ask what os I am running (since nothing works) and I tell them Debian. They sometimes keep trying, most of the time they hang up.