1. What does it mean?
플렉스 borrows flex. In Korean consumer slang it often means spending proudly on something desirable, treating someone, or jokingly making a purchase feel extravagant. It can also retain the broader sense of showing off.
Also written or said as 플렉스하다, peullekseu
2. The nuance
The purchase need not be truly expensive; a small treat can be ironic 플렉스. The word celebrates a moment, not whether the spending fits someone's budget.
3. Examples
“첫 월급으로 좋은 의자 하나 플렉스했어.”
I treated myself to a nice chair with my first paycheck.
“오늘은 내가 간식 플렉스할게.”
I'll treat everyone to snacks today.
Sources
References support the meaning and usage. Example sentences are written for NoCapWiki.