The other day, I overheard two gyaru (¥®¥ã¥ë, gals, i.e., fashion-conscious girls) talking, but I had no idea what they were saying.

¡°Oh my goodness! I was doing KS! I gotta reply now!¡±

What is KS? The hint is that the girl was doing something with her sumaho (¥¹¥Þ¥Û, smartphone).