between you, me, and the bedpost

Prepositional phrase

idiomatic

(idiomatic) between you and me

Japanese Meaning

あなたと私だけの、内密な話（秘密にしておくべき事柄） / 二人だけの秘話、あなただけと私だけの間のこと

I shouldn't say this, but between you, me, and the bedpost, I suspect she's been exaggerating her qualifications.

言うべきではないけど、ここだけの話だが、彼女は経歴を誇張しているのではないかと思う。

Sense（1）

(idiomatic) between you and me

Between you and me and the bed-post – young master’s quarrelled with old master.

between you

（ canonical ）

and the bedpost

（ canonical ）