A while back, about three years ago, I was in college and dating a girl whose parents owned a few show dogs. We had to go and dogsit for them while they ran off on some vacation.
Given that I had a project due, I brought my PC with me and used their monitor. I never so much as turned their PC on.
After the weekend was over, her mother gave her a call. "My PC is slower now! I think your boyfriend gave my monitor a virus, and now it's on my computer!"
I still have no idea how that was supposed to work.