be (as) thick as thieves

US /bi əz θɪk əz θiːvz/
UK /bi əz θɪk əz θiːvz/
"be (as) thick as thieves" picture
1.

uña y carne, muy amigos

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.
Esos dos han sido uña y carne desde la infancia.
•
The new neighbors are already as thick as thieves with the family next door.
Los nuevos vecinos ya son uña y carne con la familia de al lado.
:
thickthick and fastthick on the groundthrough thick and thin(as) thick as two short planksfaults are thick where love is thin