Well, this thread is about what you did on your computer class, not what you did at home.
Also, I'm amazed by the fact how many of you claim to install viruses etc for "lulz". That or try to troll. Getting a virus on a computer you can access is as easy as putting the flash drive in.
Secondly, it's against all information technology ethics. Well, this forum isn't about being information systems ethics, but on the other hand I beleive there are a lot of people here who could do serious damage on your computer. This includes me, but, being a future professional, I won't do that. I challenge you to do the same.