QK - Meaning in Japanese

In Japanese, the letters QK mean a "pause" or "break" to rest. A "recess." It comes from the Japanese word kyuukei 休憩, which, as you'd expect, mean exactly those same things.

The reason why QK in Japanese is kyuukei is that the names of the letters Q and K in English are "cue" and "kay." When "cue" and "kay" are katakanized, they become kyuu キュー and kei ケイ. So the letters are read as kyuu Q, kei K, kyuukei QK.

This can also be seen in the word ecchi エッチ, which is sometimes represented by the letter H in Japanese.