Dental hygiene is important to the girls. Brushing regularly is the norm, which is why it's not surprising to find a male slave with mouth agape kneeling next to the bathroom sink. The girls need somewhere to spit while they brush, so may as well nourish the slave with the mixture of food particles and spit by unloading mouthful after mouthful into his open and waiting mouth. He has two girls to serve this morning as Lady Edyn and Miss Pris both brush their teeth one after the other, hopefully he has left room in his stomach to consume all their oral waste.