I wouldn't do anything really strange. I certainly wouldn't go to work, of course, but otherwise it would just be like any other day off. Just think of what you most want to do when you have some sort amount of time and no responsibility. That's what you do when you have a day off, and this day would be no different. I'd watch some TV. I'd do a little writing. I'd play some video games maybe.
I suppose I'd try really hard to finish any project that I hadn't finished, like if I had a story half written I'd work my ass off to get it done. It would be a real shame to start something like that and never finish it.
Of course, I can imagine doing some wild and crazy stuff like sky diving or something. Someone might even decide to sky dive without a parachute. After all, you are supposed to know when you are going to die, so you might somehow survive miraculously which would be awesome. And if you don't, you haven't missed more than a few hours.
But in real life, I wouldn't do anything wild or strange because if I liked that stuff it would be the stuff I did every day, not wild or strange at all.