Ex-gf forces me to be naked in public [MF][public]

My ex-girlfriend would play with me in public from time to time. This one happened a couple of years ago.

She brought me shopping with her one day, which was weird because she usually went alone. When we got to the mall she led me to a clothing store. She grabbed a couple dresses off the rack and headed for the changing station. She made me come inside one of the stalls with her.

When we were inside, she closed the curtain and told me to take off my clothes. She caught me by surprise because she didn’t tell me we were going to be playing, but I took off all my clothes. She put them in her purse and took out a shot glass.

“I’ll be back in 20 minutes,” she said. “Fill this up for me.” She handed me the glass, picked up the dresses, and left me in the stall naked without any clothes.

While she was gone, I could hear people going in and out of the other stalls. I was technically hidden, but I felt nervous and exposed because the stalls didn’t lock. There was only a curtain covering each stall. I masturbated into the shot glass, but I had to carefully control myself so I wouldn’t spill. For the rest of the time I had to sit naked holding a glass full of cum.