This is a rather amusing little Easter egg in which you can make your sims achieve Buddhist enlightenment. To do this, it is preferable that you pick a time in which your Sims have no work (two days in a row should be fine) and then make them meditate during the entire time. Don't worry as a Sim's needs do not deplete while meditating, so they can do so indefinitely without dying.
After about 12 hours or so in game, your Sim will release a bright flash of light and begin levitating. Afterwards, every time they meditate, they will be able to hover in the air while doing so, although it takes a few seconds before they do so.