Siblings' secret tryst interrupted

A brother and sister, bound by family ties and hormones, find themselves alone and bored. Their curiosity piqued, they begin to explore their bodies in front of each other. The sister, clad in only a t-shirt and panties, tentatively touches herself, her brother's eyes fixed on her every move. He, in turn, strokes his hardening cock, their shared taboo exciting them both. Just as they're about to cross the line, a creaking floorboard signals an intruder, forcing them to hastily cover up and compose themselves.

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