I run the Canberra Rationality group. We're mostly uni students we meet once a week. Here are some of the exercises I've run that went down really well.
Have a question and take turns answering it by going around the circle. One prompt that worked well was: Say three things about yourself that make you different from the group. The little differences between us and the people we surround ourselves with can be very interesting. "I care less about grades", "I identify more with my system 1 values" or "I get less pleasure from socialising". What some people say can be very surprising. This might expose gaps in your model of them.
Some other questions include: What experiences have you had that you don't think others have? What things are you addicted to?  What experiences are you missing?
Free writing is an exercise where you write down whatever comes to mind, you try and capture as much of your stream of consciousness as you can. Even if it doesn't make sense. You try to write everything down. your aim is to fill a whole page with writing. It's okay for it to feel like gibberish. 
Free-writing is fine by itself. However if you want to take it a step further; For all the people who are comfortable sharing, pass the piece of paper to your right. Enjoy seeing other peoples thoughts, you might what to imagine what kind of person would generate these thoughts, it's sometimes strange how different other's thoughts can be.
I use brainstorms a fair bit. We made a list of things that are great. It was good fun trying to discover pleasurable things. You can also enjoy the suggestions of everyone else. Once someone says "pyjamas" or "after rain smell" you get a little buzz from imagining it which is nice.
Other topics have included: tiny projects that are neat, actions I can totally execute.
Cracks in the model
Sometimes I lead with a weird personal discovery. For example where "I" am is located behind my eyes . However if I'm in the blackness of a bath and I close my eyes it feels like "I" move further back into my head. This can sometimes open up the discussion and move us in the right direction to actually look at the world in all it's strageness.
Pull up a facebook list of your closest friends. One by one name something they seem to be striving for. Alice wants to escape, Bob pursues approval. Don't trust these simplisitc narritives too strongly but there are grains of truth. Notice how easy this is for others but not yourself. Perhaps consider ways you could assist this friend in what they're aiming for.
Most of these exercises try and target a particular kind of social knowledge. What people think about themselves, another person or the group. It's in this yummy System 1 niche. I think people really care about this kind of info. And that caring can cause them to actually look at reality.
 What would you take with you for a weekend island retreat? Paul Graham claims this tests what you're addicted to. His answer: books. http://www.paulgraham.com/island.html
 Instruciton in free writing and some good examples. http://agentyduck.blogspot.com.au/2015/01/reflective-recording.html
 Where does your mind feel like it is?https://meteuphoric.wordpress.com/2010/05/26/im-behind-my-eyes/