Mistress BlackDiamoond wanted to show her friend how to torture a slave. her friend was interested in getting a slave and it was essential for her to know how to punish him because she was going to need those skills. So mistress BlackDiamoond showed her friend how to do it and she even asked her to try it. They crushed the slave's balls with their boots and had him lick the soles of their boots.
Princess Serena did not like how this slave had cleaned her shoes. She wanted to wear them to work and he had to make sure he cleaned them again. But this time he had to do it while she wore them and he had to use his mouth and especially his tongue to do it. The mistress had him lick the boots to her satisfaction then she left for work.
Madame Svea is not an easy mistress to deal with as this guy came to find out. He did not things her way and she got pissed and instead of walking away in anger and cursing him, she humiliated him. She forced him to lick the soles of her boots and she trampled him with them. She threatened to crush his balls if he did not do as she instructed him and he did so out of fear.