(Works in groups of 4 to 15, and works best in already well established groups. Especially good for helping to break through the "niceness" barrier. Allow .5 to 1.5 hours for this exercise, depending on the size of the group; time it, and end it on time.)
Explain the game as follows: "Tonight, we're going to ask each other a lot of difficult questions. The purpose of this is to help us get to know each other better, and to become more direct in our dealings with each other. The way this works is that one person starts by asking someone else something they'd normally be too embarrassed or too afraid to ask, or that they think would embarrass the person being asked. The person being asked doesn't have to answer the question unless they want to, but they do have to ask someone else a hard question. Then that person has to ask someone else a hard question. The only limit to what you can ask is that your questions be about things that you genuinely want to know. If you feel uncomfortable when you think of a question for someone, it's probably a good sign that you should ask it. Does everybody understand? Good. This exercise will take an hour. I'll start now." Then ask a pointed question to someone you think will handle it well, and you're off and running.
Take a few minutes after you've finished for the group to discuss the exercise and what came up for individuals during it. It's also often a good idea to precede or follow this exercise with a round of appreciations.