stand on ceremony
US /stænd ɑn ˈser.əˌmoʊ.ni/
UK /stænd ɑn ˈser.əˌmoʊ.ni/

1.
遠慮する, 形式張る
to behave in a formal way, or to insist on formal behavior from others, especially when it is not necessary or appropriate
:
•
Please don't stand on ceremony; just make yourself at home.
どうぞ遠慮なく、くつろいでください。
•
There's no need to stand on ceremony with old friends.
旧友といるときは遠慮する必要はない。