Classic Magic at its finest.
The magician displays two empty bowls. He fills one with rice and inverts the second bowl over the rice-filled one. When the bowls are separated, the rice is seen to have doubled in quantity.
The rice is emptied from the bowls, and they are placed mouth-to-mouth. When they are separated for the second time, the bowls are seen to be full of water.
Easy to perform. No complicated sleight of hand involved in the operation of the trick.