What even is "low key"?

And why is everyone saying "what even is"?

If I hear one more person say "I low key got angry", I am going to get angry.

Why not say "I got a little angry" or "this angered me but I kept my self control" or "I was upset but didn't become enraged"?

Passing fads like this are frustrating because they often make it into everyday language for years to come, and then are eventually accepted as correct. It saddens me. I know English is an evolving language, but let's try to innovate in ways that make it better, not ways that make it sound like a stoned skate punk.