To let the cat out of the bag
to reveal a secret: We wanted the party to be a surprise, but he let the cat out of the bag.
Somebody’s bark is worse than their bite
MEANING: If your bark is worse than your bite, you appear to be more angry or dangerous than you really are. EXAMPLE SENTENCES: Don’t get upset if the boss yells at you. His bark is worse than his bite. If someone’s bark is worse than their bite, they get...