Yes you can turn a cup of water upside down without spilling it! This nifty “magic” trick is sure to wow family and friends, and can be done with no fancy materials or supplies.
To start, fill a small plastic cup about half way with water. Place an index card on top.
Flip the cup over with your hand firmly holding the index card in place (it’s okay if a little water spills out), and make sure the index card is saturated.
Slowly remove your hand and… the index card sticks, without the water pouring out. There’s definite wow factor here, but it’s all thanks to the simple fact that water molecules like to stick together. Air can’t get in the cup as a result, equalizing the pressure, so the heavy water doesn’t pour down.
Travis also got a kick out of the way the index card pops off if you squeeze the cup even slightly, breaking the bonds of those sticky water molecules.