How about a cane discipline? Our slave is tied by his hands and cannot defend himself. All the better so we can punish him mercilessly with our canes! We beat on his ass and his back, but also let the cane slap the soles of his feet and his belly! The loser doesn't deserve anything else and, indeed, will thank us at the end for the punishment! After we have untied him there is more caning and then he must kiss our shoes!