The Stimulation Supercriticality.

The head, hard and black, glistening from the wetness of her arousal, teased her engorged lips, nudging as if to push deep into her, then sliding easily along the puffy lips, to tease her nub, each graze pushing her further, inching her closer to the ultimate goal, an earth-shattering climax.

Beaded with perspiration, her breathing no more than strangled gasps, forced out between clenched teeth, she was silently begging for it to be over, but at the same time, praying for it to continue.

The sensation was both ecstasy and agony, sometimes more of the later, and she didn't know which she craved more. She knew she wanted him inside her, stretching her, stroking her, as he'd done many times before, but this, this was even more mind-blowing. How much longer she wondered, could she hold off her orgasm.

Forcing her eyes open, she saw the look of rampant desire written across his face, his eyes wide with fascination, at how she was responding to his ministrations.

It began three weeks and four days ago. It was such an unexpected thing, so against everything she expected of him, that, even without an eidetic memory, she would never forget the details.

It was all the result of him accidentally walking in on her, while she was enjoying a session with Gerard. He'd been shocked and horrified, he told her, but, days later, he confessed to also being a little aroused. A few days later, she'd tentatively broached the subject, and, much to her surprise, he didn't dismiss it out of hand, and a few nights later, he agreed to take control of Gerard for her.

He found it so arousing that, having spent a surprisingly long time, ministering to her with Gerard, an experience that had also somewhat aroused him, he took her to her climax, in a forceful, almost possessive way, which she actually admitted to enjoying. Over the next week or so, they had repeated the experience, several times.

She couldn't remember how she came to voice the idea, but she did, and he instantly agreed. They ordered it, and a few days later, it arrived in a plain wrapper. Despite the promises of discretion from the seller, he had insisted that it be paid for with her Credit Card.

They cancelled all engagements, and told their friends that, under no circumstances, where they to be visited or called, for the whole weekend, an instruction that caused a sly, knowing grin to grow on Penny's face.

Unboxing it, she was surprised at its size, about 10 inches long, with a hard, black, domed, rubber head, about 2 inches in diameter. Sitting naked on the bed, they considered it for a couple minutes, then Sheldon asked "Where do you want me to start?"

"Anywhere you like" she assured him. Switching it on, he considered it for a moment, then tentatively dragged the vibrating rubber tip across her left nipple. The effect was instantaneous, and literally shocking to her, an electric like sensation tearing through her body, putting almost every nerve on edge, and racing to her loins, which twisted and tightened.

Laying on her back, a pillow under her shoulders, so she could see as well as feel what he was doing to her, Amy gently moaned with each drag of the dry, rigid rubber orb, across her hardened bud. Taking it from her flesh, he let it lay on the bed, still humming, and pinched her hardened nipple between his finger and thumb, gently squeezed it, then, putting it between his lips, he nibbled and licked it, feeling the warmth, and tasting the gently scented flavour of freshly bathed flesh.

Picking it up again, with agonising slowness he stroked it down her belly, barely touching her skin at all, then, briefly skipping her mound, he pressed it gently against her, before drawing it forward, along her moist and slightly swollen lips. The effect was surprising in its suddenness. Stiffening, Amy reached over her head and grabbed the headboard. With each stroke, the friction became less, but the growing slickness made it even more arousing.

It was all she could do to breath. Her heart pounded inside her chest, her body felt hot, and her loins were on fire, but still she wasn't quite there. The thumping of her heart was so great, she could hear it, and still Sheldon went on, stroking it along her swollen lips, pausing to press it against her nub for a few seconds, before again dragging it along her lips, then it happened, an actual scream, and he knew the time had come.

Dropping the vibrator on the bed, he rolled Amy on her stomach and, straddling her legs, he drove himself into her, while pinning her to the mattress. Stroke after stroke, he thrust himself into her, savouring the scalding wetness that coated him. On and on he went, his belly slapping against her soft, full, curvaceous buttocks, then, just as he felt himself pulse, he felt her tighten around him.

Even as he emptied into her, he thrust again and again, until, totally sated, he fell onto her, their glistening bodies sticking together, rising and falling in one, from the depth of their breathing.

Feeling himself soften, he lifted himself with his hands, and slipped out of her. For a moment, she lay face down, arms spread to sides, allowing the cool air to chill her flesh, and steadied her breathing, before rolling onto her back, a huge, satisfied grin on her face. "That" she assured him, "was incredible". Flashing Amy a self-assured grin, he replied, "Glad I could be of service."

Dragging herself into a sitting position, she asked "Shower?" Nodding, Sheldon picked the vibrator off the bed and switched it off. Opening the drawer of the nightstand, he went to put it in, then he paused. "Did you know" he proffered, "that this thing is waterproof?" With a glint in her eye, Amy replied "Is it? In that case, bring it with you."

Across the hall in 4A, Penny yawned and announce to herself, "Finally, I can get some sleep." Sheldon had been right, those noise cancelling headphones were not very effective.