While in graduate school, I worked afternoons and evenings in an office. After 5:30pm, I was the only one left.
One evening, the cleaning crew came in and a 25ish heavy set girl came in and asked if she could empty my trash can. She had on a loose fitting shirt and when she bent over, I couldn't help but see her ample breasts. 'Like what you see?' I told her I did and she asked if I would like a closer look.
I answered 'Yes' and she closed my office door and lifted her shirt. She was braless and she had two of the firmest breasts I'd ever seen. She came over and sat on the desk and said that I had something she wanted to see. I told her to help herself, and she reached round and pulled down my zipper. I stood up and she pulled down my shorts and began fondling my penis. She used both hands for a while and I was getting pretty close to ejaculating. She got out a cloth and began jerking me very quickly, finally making me come in buckets. She came to clean three nights a week and we got to know each other very well.