"To Butter Up" is to praise or compliment someone in hopes for something in return.
That student always butters up the instructor because he hopes to get a good grade.
Fortunately, the instructors here have a lot of integrity and do react to being buttered up. Only high-quality work positively affects the grades.
Can you you just ask me for a ride to campus instead of trying to buttering me up with unrelated compliments?
Just answer the questions as best and as honestly as you can in the interview. Buttering up the interviewers will not help you get the internship.
I am insulted when someone tries to butter me up--I would rather them just directly ask what they want from me.