생색을 내요 · 생색을 냈어요 · 생색내지 마세요
to make a show of one's kindness; to take credit for a favor
Example
커피 한 잔 사 주고 하루 종일 생색을 내요.
He bought me one cup of coffee and has been making a big deal of it all day.
Word parts
생 produce+색 color
Literally 'to bring out color' — making your favor visible to everyone.