‘To be a bad egg’
My colleague is a bad egg. He never tells the truth.

‘Like a rabbit caught in the headlights’ 
I was doing a presentation in front of a huge audience and I was like a rabbit caught in the headlights. 

‘To walk on eggshells’
I have to walk on eggshells with my boss because she gets angry and upset very easily.

A spring chicken.
At 87, he’s no spring chicken, but he still does the gardening every weekend.

To hatch a plan.
They hatched a plan to surprise their sister with a huge birthday party.

‘To be a bad egg’ My colleague is a bad egg. He never tells the truth.