Break a leg
Unknown; many unproven and widely debated theories exist. One of the most plausible is that it comes from Yiddish הצלחה און ברכה (hatsloche un broche) through the heavy Yiddish influence in the American theater, from German Hals- und Beinbruch (“neck and leg break”), perhaps a corruption of the Hebrew הַצְלָחָה וּבְרָכָה (hatslachá uvrachá, “success and blessing”).
- (idiomatic) To perform well in a theatrical production or comparable endeavor.
- Go out there and break a leg tonight. Put on a great show!