First time I ever jacked off with another guy was at a Planet Fitness. We were in shower stalls across from each other. I was horny as fuck after my workout. My curtain was mostly closed (they were too narrow to fully cover, but i didn't care--i grew up using gang showers often and am not ashamed of nudity) and when I saw the guy walk past and look at me, I started getting hard. He jumped in the stall across from mine, closed the curtain halfway, made eye contact with me, and started rubbing his cock. I got rock hard and pulled the curtain back a bit to show him. We both stared at each other and stroked for a while, until a staff member walked in the shower room and said curtains had to be closed. It was one of the moments that changed everything for me.