19 September 1961, The Hills reported the first alien abduction experience to be widely spread in English-language publications. While driving home, they observed a light move through the sky and land ahead of them. Barney Hill said that, against his will, he turned the car down a side road towards the light, where he found six small humanoid beings waiting for them. Betty Hill reported that they inserted a needle through her navel among other vaguely medical tests
So if you identify a UFO as a UFO, it becomes an FO, unless it has landed...then its just an O.