out with it - Phrases/Idioms
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Say it, as in Tell us what you really think—out with it! Used as an imperative, this idiom uses out in the sense of “public.”