a word used by Eleven (Stranger Things) on her look. She was dressed up in dark clothes and had black eyeshadow smudges and slicked back hair. It could mean that you look punk/grunge etc. or a type of vibe you feel
Please refer to the song Deceptacon by Le Tigre. When attempting to limit your description of this song to one adjective, the appropriate adjective will be the word "Bitchin."