It's not what the slave dog usually drinks, but it's what he gets to drink today! He's thirsty, so out of desperation he's now drinking Mistress Anfisa's spit! She takes him on the leash, spits a large portion on her hot leather boots and lets the slave lick it all off. No drop should remain. Mistress Anfisa shows generosity and wants to quench the thirst of her slave dog, but only with her spit, because normal water is completely overrated!