Keep something a secret.
There are four origins of this idiom (I GUARANTEE IT):
- English archers protected their bows by putting the strings on their heads under their helmets;
- “keep it under our hat” was mentioned in 1982 in periodical "Gleanings in Bee Culture";
- President
Abraham Lincoln's stove pipe hat, where he kept important papers;
- the ceremonial swordbearer of
the Lord Mayor of London (can be dated to
1420), who keeps the key to the Lord Mayor’s seal of office in a special pocket in his hat.
-keep it under one's hat-
Joey:
All right, what else?
Chandler: Well uh, there was acting classes,
stage combat classes, tap classes…
Joey: Which we're still keeping under our hats!
