Ever find yourself at the at the water cooler only to discover it's out of cups? Do you work in an office*? For the sake of this analogy, let's say you do**. Well then, you're in luck, as most offices contain paper, which is the main ingredient in a paper cup. Let's go!
*Even if you don't work in an office, this is a quick and easy trick.
**But seriously, play along. You're in an office, sans cup
Step 1: How to Fold a Triangle
Hey, I told you this will be easy. There are only 2 things you'll need: A sheet of paper and some sort of liquid. Ignore the liquid until after you've dealt with the paper. You need to fold the paper into a triangle. You can either cut off the overhang, or just fold it to the outside like in the pictures. The triangle should be able to open up into a square. This is important.
Step 2: More Folding!
Now take one of the triangle's points and fold it over to the edge. Try to get the newly created top line parallel with the bottom of the former paper triangle (pic 1). Fold the other point the same way.
Step 3: Fix the Flaps
Fold the top flaps down over each side.
Step 4: Finished
Open up the middle and fill with your liquid. I drank 3 glasses out of the same cup. I probably could have tried several more, but my thirst was quenched.