Piece of cake
like 2 peas in a pod
Bun in the Oven
Rome wasn't built in a day
When pigs Fly
Elephant in the room
Finding a needle in a haystack
Kill 2 Birds with one stone
As easy as ABC
The early bird catches the worm
Let the cat out the bag
Eagle Eyed
Once in a Blue Moon
Feeling under the weather
sick as a dog
Like a Fish out of water
head in the sand
I smell a Rat
Break a leg
best thing since sliced bread
spill the beans