A perfect all-kill happens when a song is #1 on all major real-time and daily charts, as well as iChart's weekly chart. It's a big feat that doesn't happen to everyone (a regular all-kill doesn't include the daily charts or the weekly chart).
Not only so, but the girls hit MelOn's roof, meaning that their song is charting higher than the standard graph allows.
Congratulations to the girls!
Tip: Krizia Maranan