A plasma shock is a physical experience caused by contact with plasma that is very painful but doesn't cause any lasting physical harm. It is also strong enough to overload the neural net of a Soong-type android like Data.
Lieutenant Commander Geordi La Forge and Ensign Ro Laren tried to plasma-shock Deanna Troi, Data and Miles O'Brien in 2368 when they were taken over by Ux-Mal criminals. The shock was powerful enough to send Troi and O'Brien to the ground and made the criminals temporarily leave their bodies. (TNG: "Power Play")