What does kpop fog mean?

It means telling some jokes about Korean pop music.

Kpop is a kind of pop music in Korea, and it is also a kind of music. Fog, as a network term, means "all wet". It is used in the network to prevent improper use of words or joking language from causing adverse consequences, but it also wants people to see it, so a fog is added behind it to prevent people from taking it seriously.