It's a meme everyone. In disguise.
Well, actually, it randomly turned into one.
What you do... is make any character, including UTAUs, do this little animation thing that Teto's doing... with the mouth, if you want.
Optionally, you can also make your UTAU sing it. Your choice. (I'm not so fond of the UST out for it by Sachi Eika's voicer though)