A lock has a base with lip extensions which fit about the flange extensions of a ball hitch receptacle to cover the ball receptacle opening. The base is secured by a spring loaded latch having a ramp-shaped upper surface which is forced downward by a flange of the ball receptacle bearing against the ramp when the lock is installed to spring upward within the receptacle when the latch clears the flange where it opposes the removal of the receptacle. The latch also extends downward through a slot in the base part which has a downward projection where the latch is pivotably connected. A hole in the downward extension of the latch can receive the shackle of a padlock to secure the latch fixed to the base projection which holds the upward latch extension within the ball connector to prevent the removal of the lock from the connector. The lock is removed by first removing the padlock and then by pulling the latch downward by its downward extension while simultaneously sliding the lock clear of the ball connector.