I have done it with 3 women that I remember.

One was a date; we had met at my office and left for the date; we did it when we came back from the date on a coworker's desk (I had too many papers on mine) and on the floor. She was concerned that there might be surveillance cameras, but that didn't stop her. This was about 10:30pm and there was no one else in the building.

The second was a cleaning woman in her 20s who was working with her parents. Once or twice a week, I did her in one of the cubicles where I knew there was no surveillance. This was usually around 6pm and there would usually be 5 other people in the building, including her parents, my boss and a project manager, but most of them were always downstairs.

The third may not qualify because it was only a blowjob in the front seat of my car in the parking lot at work, but it was the riskiest because it happened during lunch.

Two other coworkers fellated me during lunch, but we were not at the office.