When you take an empty water bottle (usually the half-liter size) and begin twisting it in the center while the top is still on. Once you've twisted it to a point where you can go no further, you aim the bottle and carefully twist off the cap. The pressure inside of the bottle shoots the cap off and makes a distincive 'pop' sound. Failure to remove the cap quickly enough usually results in a 'fizzler'.
"A true bottle pop can go as far as 100 ft."