- Egg, hardboiled and in its shell
- Milk bottle
- Soak the egg in vinegar until the shell becomes soft.
- Lay the bottle on its side.
- Gently squeeze the soft egg through the neck of the bottle and let it slide to the bottom.
- Rinse the bottle with cold water to remove the smell of vinegar and to make the shell harden again.
- Now you can show this amazing achievement to your friends! (But don't tell them how you did it.)