Type "would you rather" and then post any two choices of actions, then the next person to post has to say which of the two actions he would do, then he posts two choices of actions and the next poster chooses and so on.
FOR EXAMPLE
Would you rather
- Read out your most embarrassing secrets to your whole school?
- Walk around naked in the cafeteria during lunchtime?
You get the idea. Next person to post answers the example.