Getting an object into a container which it cannot fit into without damaging it, is a seemingly difficult procedure. The hard boiled egg into a bottle trick has been performed for over 100 years. By using temperature to change the air pressure inside the coke bottle, you can create a vacuum to suck the egg into the bottle. You should take the shell off the hard boiled egg to attempt the trick.
Rinse out the coke bottle to remove any residue. Let the bottle dry out
Set paper strips on fire using matches and quickly place them inside the bottle.
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Place the hard boiled egg on top of the bottle immediately. Make sure that the egg is sitting upright.
Wait for the burning paper to heat the air inside the bottle increasing the air pressure. When the fire goes out the air will cool, reducing the pressure and creating a vacuum. This vacuum will pull the egg through the neck and into the bottle.
Striking the matches should be performed by an adult.