Up the ass
You know that look of shock a dog gives when a vet takes their temperature? Well, why not do the same thing to your leashed slave girl with a large dildo , It’s great fun and the squeal she gives out is most satisfying especially if she wasn’t expecting you to do that. As a bonus, once she has gotten used to having the butt plug inserted in her bottom, it’s much easier to fuck her in the ass too! 🙂