Alone time in the shower.

As she undressed and got into the shower she couldn’t help but think again of the time she saw him masturbating. Before that incident she had seen him naked a number of times, but never saw his huge dick hard before. And it was very big, when she saw him jerking off he was sitting on the edge of his bed leaning over, and his penis nearly came up to his chest. She realized with a slight pout that size down there is just one more thing for him to outmatch her at, looking at her tiny dick in comparison. Though curiously, it didn’t look as small as she remembered it being in her room moments earlier, though she has a different angle on it now and she wasn’t undressed then.

As she turned on the water, she still couldn’t get the image of her brother stroking his dick out of her head, and again the tingling came as the water came down on her and steam filled the shower. Her dick began to get hard again, and this time she got excited about it in anticipation, even got more turned on from watching it harden. Elsewhere on her body something else was happening, the tingling was also in her nipples, growing harder than they ever have before. She stared at them in fascination, easily comparable to the eraser on a pencil sticking out of her dark quarter-sized areole.

Heart racing, she reached down and started to rub her penis, and bringing up earlier suspicions she noticed that it even felt larger than before, although she was holding it properly now and not rubbing it through her thin panties- it still felt at least 2 ½ inches long now, an entire inch longer. This thought strangely excited her even more, the thought that it was bigger was an unexpected thrill to her, and introduced the thought that it might keep growing.

Her penis was painfully hard now, she was so over stimulated by all the thoughts, and after only barely having to rub it she let out an orgasmic “GUH!!” and cum shot out of her cock with such **** it made a “splat” sound as it hit the shower wall. This orgasm was much more intense than earlier, and even produced more cum than before. Maybe the first time was just a practice run eh? She felt weak and leaned on the side of the shower as her body trembled as the tingling spread through her body as before, causing her to groan. After a moment she gathered herself and finished her shower.