What does Black Ocean mean?

Black Ocean meaning in Urban Dictionary

During shows followers will flail their cellphones and light sticks since the artist(s) performs, generating an "ocean" of light from the viewpoint of performer. A "black ocean" is a trend in K-pop (Korean Pop or music) where in fact the audience turns off their particular light sticks and cellphones as a show of lack of help to the present group onstage. When done collectively, it seems towards the performers as a "black ocean" as a result of the decreased lights from the audience. Generally just takes place in acute cases. However, "extreme" is a subjective word when it's put together using craziness and stupidity that's the hardcore fans of K-pop.