What is the salt and ice cube challenge?

The salt and ice cube challenge involves placing a cube of ice on a person's skin, typically their forearm, and then sprinkling salt on top. The salt lowers the freezing point of ice, causing it to draw heat from the skin and create a burning sensation. Participants often endure this pain for a short period to test their pain tolerance. It is important to note that this challenge can cause skin damage and is not recommended.