Joyriding is taking someone's vehicle without the owner's permission.  Unlike stealing a car, with joyriding there is usually some relationship between the owner of the vehicle and the person that took the vehicle.  For example, if a person takes their parents care without their permission, that would be joyriding. 

Under South Carolina law, if the person took the vehicle for a temporary purpose only, that would be a misdemeanor punishable by up to $500 in fines and 1 year in jail.  If the person took the vehicle for a longer period of time, he or she could face up to 3 years in prison. 

S.C. Code Section 16-21-60.