Mistress Agma and mistress Jucy had to get info from this girl and they decided to humiliate it out of her. That is why they chose to trample as well as humiliate her using their feet and socks. The socks were stinky but she could not do anything about it. She was forced to lick them clean and she did it to avoid pissing them further. And she gave them all the info they sought.