I once saw a street performer do this, and its an easy trick, if you have good balance...
You start by turning with your side facing your audience. You keep the foot on the side facing your audience flat and still. Slowly raise yourself up with the ball of your other foot, which is hidden behind the leg facing the crowd. Your front leg will look like it is floating and the crowd will be tricked into assuming the other foot is off the ground too. When practiced and done correctly, it looks very believable!!!
You start by turning with your side facing your audience. You keep the foot on the side facing your audience flat and still. Slowly raise yourself up with the ball of your other foot, which is hidden behind the leg facing the crowd. Your front leg will look like it is floating and the crowd will be tricked into assuming the other foot is off the ground too. When practiced and done correctly, it looks very believable!!!