(Only works on bottled beverages with screw-top lids.)
Step 1: The Method.
For soft drinks and lightly disturbed beer, this works much faster than the "tap-the-container" method or just letting it sit.
(This only works for bottles with screw-top lids.)
1. Drop or knock over a bottle of carbonated beverage.
2. Swear because it's the last bottle of said carbonated beverage in house.
3. Remember this Instructable. :)
4. Open the lid and wait for the bubbles to start rising, then quickly reseal the lid. (This could be anywhere from 1/4 second to 2-3 seconds).
5. Wait for the bubbles to all rise to the top of the beverage.
6. Reopen and drink.
Beer is a lot frothier than soda drinks, so between steps 3 and 4, you may have to let it sit for 5 minutes. It will still get the last bit of fizz out of the beer though.
Step 2: The Science
This is how carbon dioxide can be forced into a liquid such as water under high pressure, and only bubble off slowly when the container is opened. Usually bubbles will form on the walls of the container because it contains scratches or irregularities from the bottle-molding process.
However, if you disturb the liquid, lots of fine microscopic bubbles are formed, just waiting to grow and explode into fizzy mayhem.
By using the open-reseal method, these microscopic bubbles are allowed to grow large enough that they will rise to the top of the beverage, but prevented from growing so large that the beverage will fizz over. This removes the microscopic bubbles from the liquid, and allowing you to reopen the bottle to gently fizzing deliciousness.
Obviously this doesn't work with tab-cans or bottles with non-screwtop lids. :)