Step one:

Start with the opposite side of the paper down on the table. The side you want on the outside of your cup should be face-down on the table.

Step two:

Bring one corner over to the opposite corner.

Step three:

Fold and crease. This fold should be across the diagonal middle of the paper.

Step four:

Bring the right corner of the paper about two-thirds of the way across to the opposite side. (check out the next picture, top view.)

Step five:

Do the same thing with the opposite corner, as shown.

Step six:

You'll see two flaps at the top. Bring one flap down OVER the two corners you just folded over.

Step seven:

Turn the cup over and bring the other flap down on the other side.

Step eight:

Fold and crease the flaps.

Step nine:

Puff out the cup with your hand.

Step ten:

If you like, you can shape it even more.