In the dimly lit room, the enticing scent of arousal fills the air as Mr13Incheslong's massive, 13-inch cock tents his pants. His sister, drawn by the tantalizing bulge, can't help but stare, her pussy throbbing with anticipation. She tentatively reaches out, her small hand wrapping around his monstrous shaft. He groans, his hips bucking as she strokes him, her eyes widening at the sheer size of his manhood. Their breath hitches as they realize they've crossed a taboo line, but the hunger in their eyes tells them there's no turning back.