TWICE performed 'Like OOH-AHH' at a 'Sudden Attack' event on June 11th. Almost at the beginning of the song (1:14 in the video above), Momo's tanktop becomes undone from the back. She has to grip it from the back, meaning she has to do the choreo with one hand. Tzuyu tries to help her at 1:40 but the tanktop becomes undone almost immediately again. She attempts at 2:57 again without any success.
Nayeon notices at 1:56 (she looks back at Momo even when she's walking forward) but can't get herself in a position to help her. She keeps looking concerned at 2:35.
However, Momo kept up a bright smile and danced perfectly during the performance, even managing her dance break with one hand behind her back.
Check out the video above!