I was serving in the army and went into a small library on a military base years ago, I must have been about 22 and dressed in short running shorts and honestly accidentally flashed the librarian as I crouched to look at a book. We were the only two in the small library, and she came up to ask if I needed a hand. She was way older than me but gorgeous with big boobs, and I got a little flustered as she stood there as my cock just went hard in about 10 seconds. It started poking out uncontrollably and far too obviously. It was like trying to hide a pole in a tent, not easy! It was quickly obvious, and eventually, I had to cover things up and go, and she clearly loved it.
I was very flustered by the experience and had decided never to go in that place again when guess who I bumped into at the NAAFI shop just the following week, yes, the same librarian with a shining smile and a warm, welcoming voice. All she said to me was, "I hope to see you back in the library in those short shorts, Wednesday afternoons are far too quiet". Well, that was an invitation I was not expecting, and Wednesdays were sports afternoons, so everyone went off to play football or whatever they did, and no one went to the library, so I did.