Examples:

• Keep it under your hat, and we'll be all right.
• But you got to keep it under your hat, okay?
• Keep it under your hat, but we found one of the girls.
• Now that you know, I wish you'd keep it under your hat.
• Keep it under your hat, will you?
• Maybe, but keep it under your hat, will you?
• Dan. Keep it under your hat, but we found one of the girls.
• Keep it under your hat.
• I want you to keep it under your hat.
• Keep it under your hat, I dream sometimes, even when I'm awake.