This happened when I was tutoring in college
I worked as a tutor on campus, trying to pay off some of my student loans. I mostly tutored students in economics and statistics. Usually sessions were about an hour. My tutoring sessions were held in one of the private rooms in the library, far off to the back. I tried to keep things academic, getting students in and out as quickly as possible.
One day an incredibly beautiful girl came in. She was about 5'5", long brown hair, big eyes, medium sized boobs, and a great ass. We started out normally, discussing her strengths and weaknesses in statistics. When time was up she asked if we could spend an extra hour working out some problems. I agreed.
While we were going over her notes she began to look nervous, shifting around in her seat, not really paying attention. I asked her if everything was ok. She said it was kind of embarrassing. I said I didn't mind. She slowly told me that she really needed to "relieve herself." This caught me totally off guard. I jokingly suggested that she just do it here. Her eyes got really wide and she asked if she really could.
I fumbled around, looking for the right words, but she already had her hand down her jeans. I watched, mesmerized as she moved faster and faster, her breath getting heavier and heavier. Soon she let out a little whimper of a scream as her body relaxed. She removed her hand from her jeans, adjusted herself, and stood up. I just sat there staring.
As she walked past me to leave, she put her hand right under my nose, to get a nice smell of her sweet pussy. She never came back for tutoring and I never saw her on campus... But the memory has provided me with many happy hours alone. Cheers