What are some things we know about black holes?

 I'll try to make a list:

1. The Universe Accelerates : If you're traveling toward the hole, as you approach it, space is curved so strangely that the outside universe will be seen in a small circular patch (the entire 360-degree view would be in that patch). You'll also see the universe accelerating forward (but you won't be able to see the entire future of the universe).
2. Nothing can ever enter a black hole : A black hole isn't a thing! Just as a hole in a paper isn't a thing, it's the absence of paper. Similarly, a black hole is a hole in space-time. Notice how I said space and time. So time ends right at the edge of the hole! That's right, time ends there. So there's no time beyond that. So nothing can ever enter a black hole, because no event can take place inside a black hole (and entering a black hole is an event). So if we throw a donkey toward the hole, we'll see it slow down strangely as it gets very close to the hole. But then it would take an infinite amount of time to pass through. It would be in suspended animation near the edge of the hole.
3. You can enter a black hole : While nothing can enter a black hole as seen by an outside observer, if you were to jump in, you would definitely enter the black hole from your perspective. See how weird that becomes? All observations outside the black hole will argue that you never entered. But you think you did. While only one point of view is supposed to be reality, both are real from their perspectives. Relativity at its finest, eh? Besides, you can never truly escape once you've "entered"!
4. The roles are reversed : now that you've entered the black hole (in your reality), there's no escape. Not only is there a crazy gravitational field trying to crush you, but there's no escape (literally). Outside the hole, we have the freedom to go wherever we want in space, but no matter where you go, you can never escape time. Let's say, next Tuesday, your future time is fixed, but space, not so much. Guess what? Inside the hole, time and space switch roles! You're free to choose the time you want, but your future in space is fixed. In other words, no matter what time you choose—past, future, present—you'll end up falling toward the center of the hole. (It's so freaking weird.)

Let me know if you find these facts interesting enough :)