The tip of the dildo pressed against my hole then, bigger and thicker than her fingers, the rubbery head nudging insistent. She held my hips steady with both hands, pushing forward inch by inch. The lube helped it slide, but the stretch was intense, my ring burning as it gave way around the girth. I gripped the desk edges hard, knuckles white, trying to breathe through it. 

'Fuck, you're so tight back here,' she groaned, her voice rough with effort, her nails digging into my skin just a bit. 

She kept going until she was all the way in, buried deep, the base pressing against me. She stopped there, holding...