The Roll 'n Rocker is an NES accessory developed by LJN Toys. The device was designed for the player to step on the Roll 'n Rocker and control the D-pad with the player's feet. The NES controller was plugged into the side of the Roll 'n Rocker so the player could control the A and B buttons. The Roll 'n Rocker worked very poorly or not at all with all NES games and had a tendency to malfunction often.
References
Roll 'n Rocker Wikipedia(Text) CC BY-SA