Met a girl and her boyfriend she locked in chastity at the beach

A few days ago the whether got dramatically hotter. My girlfriend loves swimming and the beach isn't very full since only a few days before it was still 30F out so we decided to go. There's a small side area separated by a sandy hill, it's not a difficult climb but not a lot of people go there so it's our go to spot.

Me and my girlfriend were walking up the hill and we heard some giggling. Getting to the other side we see a couple butt naked who quickly cover themselves with both of them using their hands to cover their crotch. The girl was using both her hands to cover her crotch leaving her boobs completely out. She used one hand to give us an awkward side wave and apologized for their state of undress.

My girlfriend laughed it off and told them that we didn't care. She also told them we've been naked in this area as well (a half truth since she's been topless there in the past) so they shouldn't worry about it. In response the lady slowly uncovered herself and asked if we'd like to join them, I looked over to the boyfriend who was still covering himself and his face was bright red.

We pull out our towel next to them and spend 15 minutes chatting them up with my girlfriend getting especially close to the female stranger. She told us her name was Cass and somewhat randomly blurted out what we thought of being kinky in public. We tell her we don't mind it and even partake in it sometimes and she sheepishly asks what we would do if we met someone "doing kinky stuff in public." After hearing us say it'd be cool (I said it'd be cool my gf said it'd be hot) the couple look at each other and the man slowly lifts his hands and exposes his penis which is locked up in a chastity cage leaving my gf and I shocked.

As much as I'd love to end the story with a super hot conclusion with a bunch of SPH, I'll be honest we just hung out and became friends. We shared numbers so it's nice having friends into kinky stuff but we didn't do anything else that day.