keep it on the down-low
keep (something) on the down low
To keep something in a state of secrecy or minimal public knowledge; to not share something with anyone else. Keep this on the down-low, but Janet is planning to break up with Kevin next week.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
keep it on the ˈdown-low(American English, slang) keep something secret; not tell other people about something: Her parents wouldn’t approve of our relationship so we keep it on the down-low.
Farlex Partner Idioms Dictionary © Farlex 2017