When we saw my sister following that man into the men's showers, my father and I followed her. The facility didn't allow us to watch secretly, so I immediately decided to step out into the open and shamelessly began to watch them, stroking my cock. My father initially remained hidden, but then, drawn by my sister's moans, he too abandoned all restraint and positioned himself next to me. The expression on my sister's face told us how excited she was to see us there together, masturbating for her...