He tries to resist... but not that much

Matt's first instinct was to back away, but up against the corner of the counter as he was, going past his sister was the only way he could move. Instead he grabbed her hand lightly, trying to pull her off, but she resisted, and he succeeded only in stopping her motion. This restored just enough blood flow to his brain for him to squeak out a 'What the hell?' before she lightly batted his hand off of hers and resumed stroking.

"What the hell are y-you doing?" Matt tried again, as Clair began to put some rotation into her dick handling. He again tried to pull her off, although he was having trouble concentrating. As a virgin, this was the first time anyone else had had their hands anywhere near his cock, and the feeling was nothing like what it was when he jerked off.

"What's wrong Matt?" she asked, giving him a tight squeeze that made him gasp, then running her thumb up the center. "You always said you liked my massages."

"But what about Brandon," Matt replied weakly, his resolve going down as steadily as his dick continued to harden.

"Oh, he likes them too. He once told me that he was glad I had so much practice from being a gymnast," she replied conversationally. Then, giving him one final stroke, she leaned forward and swallowed Matt's dick halfway, swirling her tongue around the head.

Matt's was completely lost in pleasure at this point, and even unconsciously reached down and gripped Clair's head lightly, trying to get her to go further down on his dick. Her clearly skilled mouth felt soooo good, he wanted more.

And then their mother walked into the kitchen, and the sudden reallocation of blood to the other end of his torso was so fast that Matt got a light head rush.