If you name something, what are you doing to it? You're identifying it, right? Well, in that case, it's impossible to have a UFO.
In order to be called a UFO, the object would have to be identified as a UFO, at which point it could not longer possibly be a UFO, because the U stands for Unidentified. As the object has just been identified, it can no longer be called a UFO. Then, if we don't call it a UFO, it's not identified, and if it is a flying object, would thus be an unidentified flying object.