[MFN]

Yes, I did once observe someone fucking. At the beach, I first noticed her as she was lifting herself off the cock of the guy under her. While I was trying to wrap my mind around what I was seeing, she pulled a different guy down onto her blanket who ate her then fucked her, to be followed by another fellow. Some sort of high-class gangbang? But she seemed to be the one in control. Between fucks she got up, pulled on some shorts and a top, and mingled with the other people in the crowd (this wasn't a nude beach). Then she'd pick out a different guy, get him to her blanket where they both stripped off and fucked. The other people there either ignored the copulating couple or casually chatted with her while she fucked. She seemed to be capable of keeping up a conversation while fucking, and she lost the thread of the conversation only during her orgasms.

Even though I was a newcomer at the party, I made her acquaintance and talked with her as she leaned back while being eaten out or straddled a cock (not mine). She had several orgasms as we talked and got to know each other. So not only did I (and numerous others) watch someone having sex, I talked with her as she took on several partners.

So yes, I did once observe someone having sex.