let (one) in on (something)(redirected from let him in on)
let (one) in on (something)
To give one information that is private or not widely known; to include someone in something. All right, I'll let you in on what’s really going on here—we're planning a surprise party for Carla.
let in on
Allow someone to know about or participate in something, as in I'm going to let you in on a little secret. This idiom was first recorded in 1904.
let (someone) in on
1. To reveal (a secret) to someone: They finally let me in on their plans.
2. To allow someone to participate in (something).