Sorry, you all fail the Repost Rule - if you declare it a repost, you post the link.
We must only hope that his revenge is sweet. I'm thinking desktop changes, and perhaps adding shortcuts to videos in the perpetrator's startup folder.
Then be ambitious - disable the laptop's shortcut buttons for volume control, change his password, and have the system lock the session right after startup. Then he's stuck at a login prompt with his laptop making "noise," without the password, or access to the volume control. Only option - cut the power.
But then, I never did like pranks.