Fall Guy
A public humble-head slave is often used as a fall guy for the sins of other men - of boyfriends or husbands who have slighted their woman. The male slave finds himself having to kiss the lady's feet and apologise to her for her male partner's behaviour, even though he himself had nothing to do with the free male's actions.
Actually, that's not quite true - in Law he is whatever the customer-mistress wants him to be. So if she wants him to be a patsy for her man, that's what he is. She may even have the slave apologise to her man, once she has kissed and made up with the latter!