Pain play
From wipipedia.org
Pain play is any form of play which involves the infliction of pain on one or more of the participants. It could involve a wide range of activities such as biting, spanking, caning or whips. There may be one victim or participants could take turns to inflict pains on each other, maybe using a turnaround.
As with all BDSM activities, it is important that everyone involved gives informed consent.