1
general::
Phrase(s): Keep this to yourself.
a phrase introducing something that is meant to be a secret. • Andy: Keep this to yourself, but I’m going to Bora Bora on my vacation. Henry: Sounds great. Can I go too? • John: Keep this to yourself. Mary and I are breaking up. Sue: I won’t tell a soul.
McGrawhill's American Idioms And Phrasal Verbs