1. What does it mean?
짤줍 combines 짤 with 줍다, to pick up. It describes finding an image you want to keep for later, often because it captures a reaction well.
Also written or said as jjaljup
2. The nuance
Saving a picture does not give you ownership or permission to repost it. 짤줍할게요 announces an intention to save; it is not a substitute for permission where permission is needed.
3. Examples
“친구가 직접 그린 반응 그림을 허락받고 짤줍했어.”
I got permission to save the reaction drawing my friend made.
“짤줍한 파일이 많아져서 상황별로 폴더를 나눴어.”
I had so many saved reaction images that I sorted them into folders by situation.
Sources
Sinjoeo Korean Slang Dictionary
References support the meaning and usage. Example sentences are written for NoCapWiki.