What do you call this behavior where gratification is felt when picking on one's or somebody's skin?
I have this one friend who feels pleasure in doing such behavior when he is bored or nothing to do even though bruises are evident on his own skin.
I think he suffers from Skin Picking Disorder, probably only apparently a pleasure:
is a serious and poorly understood problem. People who suffer from skin picking repetitively touch, rub, scratch, pick at or dig into their skin, often in an attempt to remove small irregularities or perceived imperfections. This behavior may result in skin discoloration or scarring. In more serious cases, severe tissue damage and visible disfigurement can result.
Skin Picking is now thought of as one of many Body-Focused Repetitive Behaviors (BFRBs) in which a person can cause harm or damage to themselves or their appearance. Other BFRBs include chronic hair pulling (trichotillomania), biting the insides of the cheeks, and severe nail biting.
Dermatillomania is more along the sides of skin picking.
Dermatillomania / Skin Picking Disorder is the repetitive picking at one’s own skin to the extent of causing damage.
Though this more reminiscent of Obsessive-compulsive disorder, it may also provide pleasure.