The Brief: High key is a way to describe something that is a big deal.

DEEP DIVE
High key, also stylized as high-key or highkey, is an adjective meaning “very much.” It is used to put emphasis on something, drawing attention to it. High-key is an antonym for low-key. The two words are often used in tandem with each other, thus canceling each other out while conveying mixed feelings about something.
Yeah, low-key or maybe high-key
I been peeped that you like me, you know? –Drake, “Only”
im highkey antisocial af, its not intentional. People just be vibing wrong and its distasteful
— 888 (@mtimpsonjr) December 5, 2018
High key just want a spa day, ya know:
-face mask
-hair mask
-manicure
-pedicure
-fav movie/s
-green tea
-fav candle
-oversized t-shirt
-last but certainly not least, fuzzy socks— Sophia Delgado π» (@oksophiie) December 2, 2018
high key thinking The Carol 3.0 (ot12) will be the best LOONA song ever
— fede (@hyunjinwon) December 5, 2018