letting slip

Verb

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

1. (idiomatic, transitive) To divulge a secret, as by accident or mistake.
   • It was let slip that they were planning to take over the business.
2. (UK, obsolete, slang) To let fly; to attack or challenge someone.
   • I would take it kind of your worship to let me be present at his examination, that if he clear himself of one murder I may let slip at him with the other.1862, Thomas Hood, John Clubbe, Tom Hood, Works: Comic and Serious, in Prose and Verse. Edited, with Notes, page 263