let in on

let in on (third-person singular simple present lets in on, present participle letting in on, simple past and past participle let in on)

1. (ditransitive) To disclose or tell (a secret) to (someone); to share (privileged information) with (someone); to inform (someone) of (a secret). See Usage notes below.

   Do you think we should let him in on the shortcut?

   If this is a joke, please let me in on it.

Unlike disclose or tell, the full phrasal verb let in on is ditransitive only, requiring both a direct and an indirect object.

• in on
• clue in