This is not to be taken literal, as is the case with most music. It likely is to be interpreted/ translated to terrorize a club/dance floor, much like the phrase "killer/killa" was used to kill an MC or opponent in hip hop battles or rap songs. Is it insensitive? Perhaps, but we are free to draw up our own opinions/conclusions.
We do live in a world with much violence, so it should be to no surprise if we see lyrical metaphors in pop music that use violence to represent or signify a totally unrelated action/intention.
As for the craze itself, the Harlem Shake is not new, some DJ dude somewhere decided to come up with this most recent incarnation, and the majority if these videos the participants are really not doing THE Harlem Shake. You can look up, Harlem Shake original to see what the actual Harlem Shake is.
Now we're getting way too deep over a silly ass dance craze if you ask me.
