The siblings, exhausted from their day, strip down and step into the shower together. The brother, his cock already semi-hard, watches as his sister lathers soap onto her breasts, her nipples hardening under his gaze. She reaches out, wrapping her hand around his shaft, stroking him until he's fully erect. He presses her against the tiles, lifting one of her legs, and slides into her wet pussy, pounding her hard as the water cascades down their bodies.