The current round of the Shitty Camera Challenge is called "Instant Regret", and I had my Fujifilm Instax Mini 40 in my bag to get some shots so I could play along.
The Instax Minis are a lot of fun. The pictures are about the size of business cards, so they're easy for people to stash in a wallet or pocketbook. Kids are fascinated by them, too, because they've lived their whole life in a world of screens, so instant hard copy output has a magical quality to them. I especially like the Mini 40 for its black & silver retro camera looks. It blends nicely with my X-E1 and its 23mm f/2 "Fujicron".