Masturbating on our park bench

We invite various candidates to join us on an afternoon rendezvous. Usually guys from the local swinger site. The bench itself is quite secluded, in a rather hidden nook of Waterlow Park. Some participants get very much into it and strip off almost naked. Others just pop out their dicks, aim and fire. I do love it when they bring their curious girlfriends. I definitely think they are highly aroused by the event, but they rarely join in. A shame