We all have our familiar roles and styles and after a while it can get just a little bit safe and boring. Worse still we stop seeing each other as complex and interesting characters.
Use a so-not-me party for you and your friends to break out and experiment with a persona that is just not like their usual selves.
Encourage your super well-groomed friends to come in daggy clothes; your daggy friends to come dressed up, try some cross-dressing so he comes as she and she comes as he.
Your conservative friends can dress like hippies or superheroes; trendy friends wear business gear, twins sets and pearls etc.
And you must all try to talk and act the parts too. Call yourselves and each other “Not-xxx” eg not-John, not-Jane.
You'll see each other in a new light. You'll see yourselves in a new light as people react differently to you.
Give prizes for the biggest surprise, the most extreme “not me”
It's like one massive role playing party. Have fun. And tomorrow you can go back to being yourselves. Maybe.