In the dimly lit living room, Bú cu, the elder sister, takes charge, her eyes hungry for her younger brother's meat. She kneels before him, her hands trembling as she unzips his pants, revealing his throbbing, uncut cock. She marvels at its size, her mouth watering as she strokes it gently. With a soft moan, she takes him in, her tongue teasing his tip before she plunges down, her head bobbing rhythmically. She moans around his cock, her own pussy throbbing with need, as she sucks him with increasing fervor, eager to taste his cum.