It's a ... of cake.
It's a piece of cake.
At the ... of a hat.
At the drop of a hat.
The best thing since ... bread.
The best thing since sliced bread.
It's a ... in the bucket.
It's a drop in the bucket.
It's the ... of both worlds.
It's the best of both worlds.
The ball is in your ....
The ball is in your court.
You're ... up the wrong tree.
You're barking up the wrong tree.
Actions ... louder than words.
Actions speak louder than words.
Kill ... birds with one stone.
Kill two birds with one stone.
Every cloud has a ... lining.
Every cloud has a silver lining.
Let ... dogs lie.
Let sleeping dogs lie.
Let's ... the knot.
Let's tie the knot.
I ... a rat.
I smell a rat.
Once in a ... moon.
Once in a blue moon.
Don't put all your eggs in one ....
Don't put all your eggs in one basket.
... the hatchet.
Bury the hatchet.
Bite off more than you can ....
Bite off more than you can chew.
Cross that ... when you come to it.
Cross that bridge when you come to it.
Take it with a ... of salt.
Take it with a grain of salt.
As ... as a rock.
As solid as a rock.
... the hook.
Off the hook.