A type of nurse shot used in carom billiards games. With one object ball being anchored (frozen) to a cushion and the second object ball just slightly away from the cushion , the cue ball is gently grazed across the face of both balls, freezing the away ball to the rail and moving the frozen ball away the same distance its partner was previously, in an identical but reversed configuration, in position to be struck again by the cue ball from the opposite side to repeat this pattern, back and forth. Compare cradle cannon .