His little sister could help...

John looked at Louise, his little teenage sister, and with his manhood exposed to the cool air of the room, her **** eyes unable to leave his naked crotch, he suddenly remembered the morning he’d had; in particular, the sight of her in her bunched up nighty, pulled up to her waist, showing him her lacy pink panties. He tried to flush the thought from his mind, to erase the mental image, but he kept his eyes on her in front of him now, knowing that she was still wearing the pair of underwear right now.

‘Louise,’ he whispered, before he could stop himself.

Their eyes met, and instead of rejecting him, Louise exhaled once, and licked her lips.

‘Very well.’ Doctor Harper said. ‘Louise, if you can… well, I’m sure you know how to please your boyfriend. We just want him to get an erection, if you will.’

Louise looked at the doctor for a moment, then back to John’s eyes. He swallowed at the sight of her, barely able to contain her excitement, and she took a step towards him so that her little waist was between his knees.

She slowly reached up a hand, but stopped before making contact, and looked into her big brother’s eyes, as if for permission. John found himself nodding once, feeling as if he was no longer in control of his own body, and Louise closed the distance between her fingertips and his manhood.

His little sister was curious with her movements, but as she felt his shaft, and moved along it to the head, simply stroking with the ends of her fingers, it took almost no time for the blood to start pumping to his loins. The added image of the pink panties, as well as her eager face staring at him now, was enough to get his dick to full erection in a matter of seconds.

As it grew, Louise inhaled sharply, as if surprised by the action. She stopped stroking him for a moment, but quickly continued once she realised what was happening; that she was making her big brother’s dick hard.

Once it was standing to attention, the doctor spoke up, standing slightly behind Louise, examining all the while. ‘Great. John, tell me, how does it feel now? Is there any pain?’