The image below shows a cool trick you can do to impress your family and friends.
How did the water get above the rim of the first class into the second glass sitting on top? First take an empty glass and pour in water very quickly until it stacks above the rim of the glass. Very quickly slam a second glass on top to contain the water. Right? Right!?!?! Okay, that's the WRONG way to do this experiment.
To avoid a huge mess, fill a glass of water nearly full. Fill a second glass of water such that it would fill past the rim of the first glass when poured. For the second glass, take a note card and place it over the glass. Tip over the second glass. If the note card is large enough, no water will spill out. Carefully place the upside down glass on top of the first glass. Line up the rim of each glass and slowly pull out the note card, carefully making sure the rims align. If done properly, no water will spill and there will be enough water to fill above the rim of the first glass up into the second glass.
Very cool! Give it a try!