They want you to keep degrading yourself

The dark-haired girl speaks up first. "If you're really such a slut, you should have no problem telling us all about it. Tell us more about what you are, in explicit detail." You swallow, and open your mouth to speak, but she cuts you off. "On your knees." Her hard eyes meet yours, and you slowly sink to your knees, looking up at the two girls towering over you. Your cock stands at attention, and you do your best to conceal it in the folds of your dress. "I'm a slutty little sex toy. My mistress owns me and she owns my... body. I am her little ****-girl. All I need to do is provide her with pleasure..." you trail off but they continue to look at you expectantly, so you keep going. "My mistress controls my... orgasms. I only get to cum when she allows it. I'm so horny right now, I need to see her so she'll let me cum."

You trail off again. The student responds, "hmm, that sounded like a lot of words for a sex toy." The redhead nods in agreement. "Totally. I've seen sex dolls before and they don't say much." You can't even formulate a response before she gives you another instruction. "Pull your dress down. Show us your tits, slut." The brunette continues, "yeah, and open your mouth. Drool all over your tits." You nod meekly, pulling the shoulder straps down and allowing your dress to fall, exposing your breasts to the cold. Placing your palms on your thighs, you let your tongue hang out of your mouth, a glob of drool slowly sliding down your tongue and chin before dropping onto your tits.

The two girls look menacingly down at you, cock twitching frantically. Maybe this would be enough?