Brown-nosing is the behaviour itself — all that extra sweetness toward someone in charge, done to get something back. You can point at it (“That’s just brown-nosing”) or use it like an adjective (“brown-nosing comments”). Same informal, disapproving, slightly rude feel as brown-nose, and the same crude picture behind it. Though actually, people stretch it: even a sincere compliment can get called brown-nosing if the listener is in a bad mood, so the word often says more about the speaker’s annoyance than about the other person’s heart.

拍馬屁（的行為）