Acronym for "Unidentified Faction Orientation Syndrome"
When a group of cunts, jocks or sluts support the nameless guy that nobody knows at the back of the class with no friends so they look good infront of the other factions, that said nameless person gets "UFOS" and evolves into a Level 2 "Ufo". He then usually becomes part of the group.
Also, sometimes acronym-ed to "Unknown Fucking Organ Donor" because that's all they're good for really.
Everyone else: "Holy shit, they got another one. He's an Ufo now."
Teacher: "Everyone please be nice to our new Student, Tom Yung."
Everyone: "Uh god, there's another kid with UFOS... Who's gonna snatch him first?"