Something about the term UFO amuses me- namely, the connotations it's picked up. UFO, is, literally, Unidentified Flying Object. Nothing in that states that it has to be extraterrestrial.
So what's with all the arguments over whether something's a UFO or not? If it's flying and you can't identify it, then it is, by definition, a UFO. Whether it's some alien spacecraft or not remains to be seen, but it's an unidentified flying object if it's been through the air and you can't identify it. I can launch a chicken out of a slingshot and as long as the neighbors can't tell what it is, then to everybody but me, it really was a UFO.
It amuses me how the definition has been modified to imply extraterrestrial origin.