Glass

A friend of mine told me their fear of stepping on glass hidden in sand. That's a very rational kind of fear to have, as no one can really be certain what is hidden under the surface layer of sand.

This one specific fear can however be ignored. This is due to the rough nature of sand. If glass is buried in sand, the edges are almost certainly roughed to the point that they can't pierce your skin.

This is also the secret behind the walking on glass party trick. To perform the trick, you'll require a bag of glass shards and a few glass bottles.

Break the bottles and perform a demonstration of how sharp the shards are. Place the shards into the bag. Shake the bag thoroughly.

Now pour the shards onto something like a towel (to make the cleanup easier). Spreap them out whilst sneakily placing a few of the larger pieces on the surface.

Now you'll have a combination of large pieces giving relative safety and shards of glass that have been roughed up from being mixed around in the bag.

That's all there is to the trick.