The brother and sister, both gym enthusiasts, find themselves alone in the locker room after hours. The air is thick with steam and the scent of sweat. He's toweling off, his 17cm cock hanging heavily between his legs, when she enters. She's wearing tight yoga pants, her ass on full display, and he can't help but stare. She catches him, and instead of being upset, she smiles, her eyes lingering on his cock. "You've been working hard," she says, her voice low. He nods, and she steps closer, running a hand along his abs. "Let me help you relax," she purrs, dropping to her knees, ready to take his big gym cock deep into her throat.