They mentioned in a song!! 
So i was listen to "Eleven" and i just figure it out
"1, 2,3,4,7 You make me feel like eleven" and Eleven in spanish is "ONCE"
And is not ONCE the name of Twice's fandom?
"You make me feel like a Once"
So people thinking the phrase have no meaning, or was some lolicon shit was wrong. They are saying they like Twice.
So is safe to say I've love Twice. 
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