keep under one's hat

Preserve the secrecy of something, as in I'll tell you about it if you promise to keep it under your hat. This usage alludes to hiding a secret in one's head, covered by a hat. [Late 1800s]

Common Names:

Name	Pronounced	Usage
KÓRi	-	Ancient Scandinavian
Marjo (1)	MAHR-yo	Finnish, Dutch
Dominicus	do-MEE-nee-kus (Dutch)	Late Roman, Dutch
Darach	-	Irish
Goteleib	-	Ancient Germanic
Gerda (2)	YER-dah (Swedish)	Swedish, Norwegian, Danish