To stand up, your friend has to move his head forward. Your finger stops his head from doing this and keeps his weight from shifting. Try mixing this amazing potion for your friends. It happens when you mix an acid like vinegar, lemon juice or buttermilk with a base such as baking soda. Too much of one or the other like in this experiment causes chemical reactions in certain foods which can lead to fun results.
Half fill the glass with grape juice.
Slowly pour in some of the baking soda mixture. Watch what happens. Slowly pour in some of the vinegar solution. Try alternating them.