On June 29, 1992, Michael Jackson applied for patent #5255452 to create the famous anti-gravity illusion he performed live during “Smooth Criminal”. Since they couldn't use the cables to support themselves during the live performances (like they did in the video), they developed these special shoes. The shoes allowed himself and the dancers to hook into pegs that came out of the floor during the song. They then provided support, much like a ski boot, allowing them to lean forward past their natural center of gravity.

The magic starts at 3:50. You can see the dancer on the far right has trouble coming free of his peg.

via boing boing