In the dimly lit room, Rihanna's eyes widen as she sees her grandfather's massive, aged cock standing at attention. Her heart races, a mix of fear and excitement surging through her veins. She tentatively reaches out, her small hand wrapping around his shaft, feeling the pulse of his desire. She leans in, her tongue flicking out to taste the pre-cum beading at his tip, before taking him whole into her warm, wet mouth. He grunts, his hips bucking slightly, his fingers tangling in her hair as she begins to suck, hard and fast, eager to please and be filled.