In the video, Jackson and the other dancers perform a lean that appears physically impossible.[17] The dancers lean forward 45 degrees with their backs straight and feet flat on the floor, and hold the pose before returning upright.[17] The lean moves the body's center of mass further than it can support.[17] The illusion was achieved using cables and a harness.[18][19] In October 1993, Jackson's team patented a method of performing the lean in concert using specially designed shoes that hook into pegs that rise from the stage.[17] Even with the shoes, the move requires good athletic core strength.[19]

https://en.wikipedia.org/wiki/Smooth_Criminal

So you could do it in public without the apparatus, if you had the specially designed shoes and placed the hooks ahead of time. (and had good core strength)