Like Sakura says, it's basically the same as the first song question. The real answer is Gangnam Style, but that's just because it was everywhere; I had no idea what K-pop was. My proper answer is Like Ooh-Aah, by Twice, after having it earwormed by a bloke on Twitch.
Well the first, like many, was Gangnam style. However I didn’t even know that the entire country of Korea existed when it came out so I never really count it lmao
The first time I watched a Kpop mv with the knowledge I was watching Kpop was Boombayah by Blackpink