a goody two shoes
A goody two shoes is someone who always does what they’re told, even if it’s boring, and acts like they’re better than everyone else because of it.
My goody two shoes classmate never talks during tests and gets straight A’s every year.
My goody two shoes coworker never takes a break and thinks everyone else is lazy.
My goody two shoes friend would rather stay home than go to a concert with her friends.