Super 레이 Super 이서

In the Korean comments

One comment reads, in translation, “Rei unnie does the 꿍실꿍실 (kkungsil-kkungsil, bouncy little sway) choreography too!” The playful mimetic word points to Rei’s small swaying movement as the detail to watch.

What the words mean

“우당탕즈” (udangtang-jeu, the crash-bang duo) combines the sound of things tumbling noisily with a fan-style group suffix. Here it is an affectionate, casual nickname for Rei and Leeseo as a comically chaotic pairing, not a claim that something literally crashes.