My 12 year old learned how to 'make a virus.'  
Actually, it only appears to be a virus, so he's no longer allowed on my computer, or my husbands... he's stuck on his own computer ~ and that's IT!
He learned how to do the thing where if you click on something it brings about 20 pop up windows, then executes a shut down command.  But the pop up windows, he places a message that windows has detected something or another virus and is wiping C drive.  Then it shuts down.
It doesn't actually wipe the C drive, but it makes you think it does from what he types in the message window.
I don't like surprises, so his little prank wasn't funny to me.  But he thought it was hilarious. I told him to think it was hilarious on his own computer all day long, and to stay away from mine.
I wonder if this is how master-hackers-wanted-by-the-law begin?