- 1). Choose several medium-sized eggs which are just slightly larger than the mouth of your milk bottle and hard boil them. While it is not necessary to hard boil the egg for this trick to work, it will certainly save you lots of mess to clean up later.
- 2). Wash out the bottle thoroughly before trying this trick; however, the inside of the bottle should be completely dry. Smear a bit of petroleum jelly around the inner lip of the bottle.
- 3). Strike a match and light a piece of paper on fire, dropping it into the milk bottle. As quickly as possible, place the egg onto the mouth of the bottle. Be careful as the burning paper inside of the bottle will heat the glass and you can burn your fingers.
- 4). Watch the egg start to wiggle as the air pressure inside of the bottle decreases due to the fire burning oxygen. The fire will go out; however, the force of the air pressure will pull the egg inside.
Source...