This is internet slang for HATER.
This is when someone dislikes someone or something, for no good reason. Somewhat like a devil's advocate
, wanting to be different and cause drama.
"Dang, Mike is a h8r, clownin on my friend's shoes"
"H8R- n. (hater) - Mike White.. "20:48
Mike: GO STEELERS!!!"
"She was h8in on my hair weave."
"That girl is such a h8r"