Stirred by his sister's presence, Luis retreats to the bathroom, his raging hard-on evident beneath his jeans. He unzips, revealing his massive, throbbing cock, and begins to stroke, his mind filled with forbidden images of his sibling. His strokes grow faster, more intense, as he imagines her wet, tight pussy engulfing him. Just as he's about to explode, he hears her soft knock at the door, forcing him to quickly clean up and hide his satisfied secret.