If you say that something you say is between you, me and the bedpost or between you, me and the gatepost, you mean that the person you are talking to should not tell anyone else what you have said. Between you, me and the bedpost, I'd say he was completely confused. Between you, me and the gatepost, he'd be better off without her. Note: People also sometimes use fencepost instead of bedpost. That's my opinion, between you, me and the fencepost.