tlqkf

If you write the Korean word '시발' (which means 'fuck' or 'wtf') with forgetting to change Korean keyboard mode to English mode, it will be written as 'tlqkf'. It usually used in the game which doesn't support the Korean alphabet or argent situations and makes people laugh. So it becomes a meme in Korea.

ㅅ = t
ㅣ = l
ㅂ = q
ㅏ = k
ㄹ = f