You were a very rich person. And one day you were at a slave warehouse. All of them were handcuffed and naked. The slave owner was guiding you around, soon he shows you a slave who was gagged as well as handcuffed.
He tried to keep the conversation as professional as possible, "This is Katsuki. He has a terrible mouth. He is gagged because he had made someone feel so bad they returned him. We learnt punishments like spankings and things don't work. But most of the time, sexual punishments do. With toys and such. Are you interested?"