1. What does it mean?
사생, often 사생팬, refers to invasive fan behavior that crosses personal boundaries, such as stalking or intruding into private spaces. It is a strongly negative term centered on privacy violations, not on the intensity of ordinary enthusiasm.
Also written or said as 사생팬, sasaeng
2. The nuance
Do not use it as a casual synonym for a dedicated fan or a photographer. Avoid spreading private information or making unsupported accusations about identifiable people.
3. Examples
“사생 행동은 팬심이라는 말로 정당화할 수 없어.”
Invading an artist's private life cannot be justified as fan affection.
“그 공지는 사생 피해를 막기 위해 사생활 존중을 요청했어.”
The notice asked people to respect privacy to prevent invasive-fan harm.
Sources
References support the meaning and usage. Example sentences are written for NoCapWiki.