As the sun beats down on their private poolside, a curious sister spots her brother discreetly fondling himself under his swim trunks. Intrigued, she approaches, offering to take over. He hesitates, then relents, his thick cock throbbing as she wraps her small hand around it. She strokes him expertly, feeling his girth pulse in her grip. His moans grow louder, mixing with the distant hum of traffic, as she quickens her pace, eager to make him explode.