My friends and I used our local public library to do our homework when we were studying for our A-levels back in the 70's before the internet, it was our solution to being able to share ideas and help each other get the best results we could.
Our local library was not very big, only open till 9 pm with 2 or 3 staff on duty week-day evenings when we mostly went there. The staff seemed to spend most of their time divided between the main-desk where they would register books being taken out on loan or being returned, or with a trolley of books to be replaced on the shelves after lenders had brought them back.
My friends and I used one of the tables to do our work and as far as possible kept the rules on being as quiet as possible, though we'd slip out now and again for a smoke and a chat. Over a couple of months we got to know the staff to nod hello to and whisper normal pleasantries as they went about their work. One of the staff regularly on duty was a very attractive lady of about 28 years age, to my 18 year old mind she was a bit of a fantasy; unobtainable but close enough to have some pretty hot thoughts about. This lady, let's call her Jenny, was always very friendly to us and always made a point of stopping to whisper a nice "hello" and ask how we were doing whenever she passed our table. Over time my fantasies about this lady librarian got to the point that I desperately hoped to see her there every evening and on those occasions that she was on duty I would spend the whole time with a raging erection as I watched her going about her duties. Luckily nobody could see my predicament as I sat at the table doing my homework.
After some weeks with these feelings it happened that I was looking for a particular book and came across a place where the bookshelves seemed to be placed to make a very private area. None of the other library users, not that there were many people in the library, seemed interested in the books there and it felt to me that I'd found my personal hidden place in the library. Well you can imagine, there I was in the workplace of my fantasy lady with a raging erection and a hidden corner. I just had to relieve my excitement so I stood in my secret corner and masturbated to the best orgasm of my young life. Of course it did not stop there and for the next couple of weeks every time Jenny was on duty I would go to my private corner and enjoy hotter and hotter wanking with her as the center of my desires.
I'm still not sure when Jenny realized what I was doing. Now I'm older and wiser I think she'd probably known all the time what effect she was having on me and she'd just let me think I'd found a place to enjoy my orgasms in private.
Of course the inevitable happened one evening when I was in my hidden place wanking furiously thinking about feeling Jenny's tits in my hands, rubbing her nipples and feeling her wet pussy. As I was reaching the point of no return I suddenly heard a very angry very female whisper;
"Where do you think you are? What do you think you are doing playing with yourself in a public place?" Of course it was not really a question and what I was doing was very, very, shamefully obvious. My hand stopped stroking my rock hard cock instantly and I just stared wide eyed and speechless at my fantasy lady Jenny. I'm surprised my cock did not immediately go soft as all the blood rushed to my face as I blushed bright red.
"Put it away right now." she said "Do not say a word, there are no excuses you could make for such a sneaky filthy performance. You know I should report this to the head librarian and more than likely the police too. You are going to be in so much trouble, you won't believe it."
I was struggling to get my still hard cock into my pants beginning to realize just how awful this could get. I could only look down at the floor and stammer "Please don't report me Jenny, I promise I'll never do this again ever! Just please don't report it to anybody, I'm so, so sorry."
There was a terrible silence and eventually I was forced to look up to see Jenny staring out me looking extremely angry. "I can't let you get away with this." She hissed at me "For what you've been doing you have to be punished!"
I'm sure my lips began to quiver as I begged her again not to report me to anybody. "I need to think about this" she whispered "and I need to have a proper talk with you before I make my decision. Be at the staff entrance on the car park behind the library 30 minutes after we close and I'll give you the chance to explain yourself. Otherwise I'll just have to make my report on what I've seen." I agreed immediately it seemed to be my only way out, to try and persuade her that I would never do it again and should be given a second chance.