Every once in a while, some joker calls, claiming to be from Microsoft (or Windows). They explain that they've detected malware of some sort on your computer and now they are here to help you fix it. I've known more than one person who fell for this helpful scam, and even if I didn't, I have no love for these people.
One day, upon receiving such a call, I decided to let them 'help me' fix my Windows. I started recording the call and this is the result.
Pay close attention to how they react when they find out they have been trolled. It's kind of satisfying.