Suze Orman once said in an interview that everyone should try and go a full weekend, once a month, spending absolutely NO money. Could you do it? The key to success is planning. You have to figure out in advance what your daily meals will be, how you're going to entertain yourself, how you're going to get around, and think about activities that classify as free fun.
Once you have an idea of what will work you need to take steps to make them happen. Grocery shop in advance, pick up DVDs from the library for free, collect games to play, make sure the car is filled up with gas, plan to drink coffee at home and pack yourself some snacks that are fun to eat while on the go.
Spending no money over the course of two days should be simple, right? It's amazing how difficult it actually is though. Go ahead, give it a try! If nothing else, your no-spend weekend attempt, may demonstrate how being disorganized can sometimes be expensive.