Keep something under your hat

Pro Tip 1/3

Confidentiality

Use when implying the information is confidential and shouldn't be shared.

I got the job, but keep it under your hat until it's official.

Pro Tip 2/3

Trustworthiness

It suggests trust in the person you're telling, showing confidence that they won't reveal the secret.

I'm relying on you to keep this under your hat.

Pro Tip 3/3

Idiomatic Flavor

It adds a playful or idiomatic flavor to conversations, compared to simply saying 'don't tell anyone'.

I might be moving soon, but that's to keep under your hat for now.