have a loose tongue

have a loose tongue

To speak too frequently and/or without discretion, especially as when unintentionally revealing private or sensitive information to others. You have a very loose tongue son. You'd do well to learn to keep it shut! The details of this project are extremely confidential, so make sure you don't have a loose tongue about it.
See also: have, loose, tongue

have a loose ˈtongue

talk too much, especially about things that are private: Be careful what you tell Sam — she’s got a very loose tongue, you know.
See also: have, loose, tongue