Okay, guys and girls, I have a reeeeaaaally big question. Like in, really big and really important.

I often see things like SJ replying to ELF on UFO. There are even a couple of vids on Youtube showing some of those answers and questions and so on. WHAT IS THIS UFO?!?!?! I really have no idea, can anyone, ANYONE please tell me? It can't be that no one knows! Please, if one of you knows what this 'UFO' is, then tell me?

I only found one thing that could be related to it, this one: https://twitter.com/UfoSJ

So, please? Dongsaengs and unnies (and maybe even hyungs) - I really do need your help! Please comment if you know anything about it! Or post this again if you don't know the answer and want to know it as well. And please tell me then if someone actually does know!