A really easy paper box. You can make it with any size paper, square or rectangle. They aren't too strong (being made out of paper) but they're good for a while if you take care of them. They are a good way to use up flyers and other paper in a fun and useful way.
Step 1

Fold the paper in half hot dog style (the long way). If you are using square paper, it doesn't really matter which way you fold it. Unfold.
Step 2

Fold each side of the paper to the center crease. Unfold. The paper should be in quarters.
Step 3

Fold the paper in half hamburger style (the short way). Again, if you are using square paper, it doesn't really matter which way you fold it. Unfold.
Step 4
Fold each side into the center crease, like in Step 2. Keep folded.
Step 5

Fold each corner to the crease nearest it. You should end up with an uneven octagon.
Step 6

Fold the flaps from the middle down over the triangular flaps made in the previous step. Crease these flaps well with your fingernail, a penny, or some other small, hard object. This is important because the flaps are what make the box a box.
Step 7
Pull up on the two flaps and voila, you have a box! You may have to recrease some of the folds to make your box rectangular/square, but that isn't too hard.