Her slave has a job to do. He needs to clean her filthy feet. She doesn't like socks so all the sweat from her feet has made them stink. The dirt from the bottom of her shoe is stuck, making her foot feel grimy and stinky. As soon as she sits down, she makes him smell her shoe. Then he is allowed to lick and suck her toes. He uses his tongue to scrub the dirt and grime off the bottom of her feet.