1. What does it mean?
월급루팡 combines salary with Lupin, the fictional gentleman thief. It likens taking pay while contributing little to stealing a salary. People sometimes use it self-deprecatingly on an unusually quiet workday.
Also written or said as wolgeumnupang
2. The nuance
Calling a colleague this can be insulting and unfair when their work is not visible. It is a metaphor, not evidence of theft or misconduct.
3. Examples
“일이 일찍 끝나서 잠깐 월급루팡 된 기분이었어.”
I finished early and briefly felt like I was being paid to do nothing.
“쉬는 모습만 보고 월급루팡이라고 판단하지 마.”
Don't judge someone as a salary thief just because you saw them taking a break.
Sources
References support the meaning and usage. Example sentences are written for NoCapWiki.