They've sort of added multiplayer to Skyrim via the game's new Kinect voice-control update. Not real multiplayer. Not the kind that lets two people play the game together or against each other. No, they've simply added voice commands. But when a friend barges in on your gaming session and yells "ally attack" and then "quicksave" while you're just visiting a town, well, you get the best kind of griefing that you usually can only get from multiplayer games.
"Ally attack" will start fights in towns where you might not want to start fights.
And "quicksave" will simply overwrite your last quicksave.
Walk in on your Skyrim-playing friends and do this to them. They'll love it! (They won't.)
The aggrieved player will probably want to reboot the game or at least load an old save to revert to their more peaceful version of their adventure.
Think of the fun you can have with this! Surely, this is why they didn't make Kinect voice controls speaker-specific, right? Microsoft wanted to encourage people to mess with each other. That's my theory, at least.