There's a college campus in my town that is open to people in general, so it's really common to walk around the green areas there, take your dogs for a walk or even hang out with your friends or date there, even if you're not a student. And since a few college classes finish around 10 p.m., you can still hang out at the campus by that time of day before the security staff kicks you out.
One time around 9 p.m. my ex and I were hanging out at the college campus and we got horny, so we looked for a place a little more private to make out. We found a sort of private area near the classrooms that was used to storage old furniture like desks and chairs. It was still an open area, but it was right in the middle of 2 buildings and you had to take a few steps downstairs to get there.
My ex stood up next to an old cabinet and pulled his pants down, showing me his hard cock. I kneeled down in front of him and opened my mouth wide. He held my head with his hands and started fucking my mouth slowly. As he pushed his cock deeper inside my throat, I started moaning in pleasure as no one could hear us.
A few minutes later, I heard students coming out of one of the classrooms right upstairs. I froze for a sec, as I was able to hear them and see their feet walking not so far from us. My ex just told me to remain in silence and he kept fucking my mouth slowly but deeply. I was still afraid we'd get caught, but I closed my eyes and enjoyed the moment even more, knowing that people were so close and had no idea we were downstairs. I held my ex's cock with one hand and sucked him faster trying not to make a sound. While he was cumming inside my mouth I could still hear people upstairs as I tasted his load.
Once we were done, he pulled his pants up and we walked upstairs talking to each other as if nothing had happened. One of the college campus security guards looked at us suspicious as he saw us walking upstairs but he'd seen nothing so we didn't get in trouble.