Preparing the Can:

Put the dull end of a pushpin into the center of the tab and, using the pushpin as a knob, rotate the tab 180 degrees around. Use the pushpin to pop a hole at the edge of the tab where it meets the raised horizontal bar under the tab. (This way, when the can is eventually drained, you can rotate the tab back around to conceal the drainage hole.)

Put the can into a cup and allow it to drain. To speed drainage, use the pushpin to pop as small an airhole as possible in an inconspicuous place at the bottom outermost lip of the can. This is the stiffest part of the can, so make sure there's nothing valuable directly in the way (like your other hand) if your hole-punching hand slips forward (or slips off the side the can) when you're making the airhole. It helps to twist the pushpin a bit back-and-forth slowly as you're punching the airhole. You'll want to use a light touch until you make your inital depression and then push a little harder as you fatigue the metal. Repitition > Force.

After the can drains as much of its contents as gravity allows, you may want to blow into the bottom hole to drain the last droplets of fluid out, since they won't leave on their own. When you eventually open up the can, rinse it out to remove the sticky soda residue (residue is typically not an issue for diet sodas, though).

To learn specific designs, click: DESIGNS