How to Make a Water Bottle Cap Pop Off With Air Pressure. Sometimes you just need to know how to do a few senseless tricks. Try making the cap pop off a water bottle with simple air pressure. You can even learn how to add a little water to make a spray when it pops.
Remove the label from an empty plastic water bottle. Keep the cap on the bottle. Be sure it is not too tight, but tight enough that it is not going to fall off on its own.
Squeeze the water bottle in the middle and twist it back and forth several times. If this does not work, repeat the twisting with the cap off. Then, replace the cap when you have twisted it, and put it back to normal.
Hold on tightly to the bottle, bracing it against your body. Keep your hand on the cap. Now, loosen the cap with your thumb. Only a loosened cap will pop off correctly.
Pop the water bottle cap in the direction of a large, open area. You should hear an explosion when the cap pops off.
For more drastic results, you can add water or air from a pump to the bottle.
Be sure you aim the bottle cap away from anyone within a reasonable distance. Pranks are fun to perform, just be sure you don't let it get out hand and or let someone get hurt.