Coin and bottle trick

Take an empty beer bottle and a small coin which is wider than the mouth of the bottle but no wider than the rim (a British penny is ideal). How do you move the coin without moving the bottle, touching or blowing the coin, or using another object to contact the coin and move it?

Solution:

Drip some liquid onto the coin so that a seal is made between the coin edge and the mouth of the bottle. Clasp your hands around the bottle and wait a few seconds. The air inside the bottle expands from the heat of your hands. As the pressure builds, air escapes bubble by bubble, by repeatedly dislodging the coin.