1. Fly on the wall
To be a fly on the wall means to be unnoticed while watching or listening to something.
2. Bee’s knees
If something is the bee’s knees, that means it is excellent and of the highest quality. You could also say someone is the bee’s knees.
3. To make a beeline.
To make a beeline for something means to move towards it quickly and with purpose.
4. To kill two birds with one stone.
To kill two birds with one stone means to accomplish two tasks or objectives at once.
5. Sitting duck
A sitting duck is an easy target, something or someone which is vulnerable to attack.
6. To chicken out
To chicken out of something means to back out of it because of feeling scared or worried.
7. A wild goose chase
A wild goose chase is a pointless task, particularly one that involves travel.