Abrasion as a human sexual practice involves sexual arousal from contact with abrasive substances. This can be person-to-person as in a harsh rubbing of the skin known as a dutch rub or with various substances such as scratchy wool or thistles. Use of harsh abrasives such as sandpaper or steel wool will likely cause lasting injury. Another form of abrasion play is "birching", where a person is struck or brushed with handfulls of twigs and leaves. Similar activity is done using handfulls of sand.