As the first rays of morning sunlight peeked through the kitchen window, David was in a state of pure bliss. He had been engrossed in his usual self-pleasure ritual, indulging in the forbidden pleasure of masturbation. The warm, soft light bathed his naked body, casting an ethereal glow on the taut muscles that rippled under his silky skin as he moved in rhythmic motions.

His fingers glided smoothly over the swollen head of his cock, tracing the delicate folds and veins with expert precision. The sensation was euphoric, sending electric pulses of pleasure coursing through his entire body. David's eyes were closed, lost in the sensations, when suddenly, a voice pierced the silence.

"What the fuck are you doing?"

David's eyes snapped open to find his stepsister, Sophia, standing at the kitchen door. She was clad in nothing but a sheer, pink nightgown that left little to the imagination. Her long, raven hair cascaded down her back in loose curls, and her emerald green eyes were wide with surprise and anger.

David's heart skipped a beat as he tried to regain his composure. He was momentarily stunned by her unexpected appearance but quickly composed himself. "Hey, Sophia! Just getting ready for the day." He attempted to sound nonchalant, but the lie was evident in his voice.

"Right," she sneered, crossing her arms over her chest. "And what exactly is 'getting ready' when your dick is out and you're rubbing it like a maniac?"

David felt his face flush with embarrassment, but he tried to maintain his composure. "You know, I was just taking care of some business," he stammered, trying to cover up the situation.

Sophia rolled her eyes and folded her arms across her chest. She had a mischievous glint in her eye that David couldn't quite place. He knew she had a wild streak and could be quite manipulative at times, but he never expected this from her.

"Hey, you know what?" Sophia said suddenly, her voice dripping with sarcasm. "You look like you're having a great time there. Maybe you should cum all over your hand, then you can just wash it off in the sink and go about your day."

David felt his blood boil as he clenched his fists at his sides. He had never felt such humiliation before, and he knew that if he didn't respond carefully, he would only make things worse. "Look, Sophia," he said through gritted teeth. "I was just... relieving some stress."

Sophia raised an eyebrow. "Oh, really? Well, you know what else could use a little relief?" She took a step forward and pointed at the coffeemaker on the counter. "How about you cum all over that instead of your hand? I'm out of cream anyway."

David couldn't believe his ears. He knew he should just ignore her and leave, but something inside him yearned for the challenge. He took a deep breath and decided to play along, hoping it would diffuse the situation.

"Sure, why not?" he said with mock enthusiasm. "But I need your help."

Sophia raised an eyebrow and smirked. "My help? What do you need me for, Mr. Big Cock?"

David felt his cock twitch at her words, but he managed to keep his composure. "I need you to hold my coffee cup for me while I... you know." He tried to keep a straight face as he said it, but he knew he was blushing.

Sophia chuckled and walked over to the cupboard, pulling out a ceramic mug. She handed it to David, who took it in his hand and positioned himself behind her. "Okay, here's your cup," she said, turning around to face him. "And I'm right here if you need any assistance."

David couldn't believe what was happening. He had never been so aroused by the thought of cumming in front of someone else, let alone his stepsister. But as he looked into her eyes, he felt a strange sense of excitement and taboo thrill coursing through him.

He took a deep breath and began to stroke his cock with renewed vigor. The sensation was overwhelming, and it didn't take long for him to feel the familiar tingling at the base of his shaft. He knew he was close, and as he looked into Sophia's eyes, he felt an insatiable desire to cum all over her face.

"I... I can't believe you're really doing this," she whispered, her voice trembling with excitement. "But I have to say, it's kind of hot."

David couldn't hold back any longer. He grunted and let loose a torrent of cum that splattered all over the ceramic mug. Sophia gasped as she watched the white, sticky liquid drip down the sides of the cup.

"Holy shit," she whispered, her eyes wide with surprise. "You really did it."

David felt a sense of relief wash over him as he stepped back and wiped his hand on a nearby towel. He looked at Sophia, who was still holding the mug, and couldn't help but feel a strange connection between them.

"Thanks for your... assistance," he said, trying to sound nonchalant. "I guess that's one way to start the day."

Sophia chuckled and set the mug down on the counter. "Yeah, it was quite an experience," she said with a grin. "But next time you want to jerk off in the kitchen, maybe just do it behind closed doors?"

David nodded, feeling both embarrassed and exhilarated by the entire encounter. As he walked out of the kitchen, he couldn't help but feel a strange sense of satisfaction. He knew that what they had just shared was taboo and forbidden, but there was something deeply primal and thrilling about it.

As he closed the door behind him, he heard Sophia chuckle once more. "Well, at least I got some cream for my coffee," she said with a laugh. "Thanks, Mr. Big Cock."