1. Unidentified Flying Object. Usually refers to an alien spaceship that we don't know anything about it
2. Ugly Fat Old. Usually describes women who are well past their days, and even then they probably weren't very hot. They are usually seen in public in twos or threes and the only thing they do is talk to each other no matter the circumstances.
1. That UFO just crashed down in an open field. We have no idea where they came from.
2. Some UFOs sat in front of me at the movie theater the other day and they wouldn't shut up for the whole entire movie.