be (as) thick as thieves
US /bi əz θɪk əz θiːvz/
UK /bi əz θɪk əz θiːvz/
1.
親密無間, 情同手足
to be very close friends and share secrets, often in a way that excludes others
:
•
Those two have been as thick as thieves since childhood.
那兩個人從小就親密無間。
•
The new neighbors are already as thick as thieves with the family next door.
新鄰居已經和隔壁一家人親密無間了。