Raining cats and dogs
It's raining really hard
Couch potato
A lazy person
At the drop of a hat
Immediately
At the end of your rope
No more patience
A frog in your throat
Your throat is dry and it is difficult to talk
Spill the beans
Tell secret information
A needle in a haystack
Difficult to find
Break a leg
Good luck!
Tell someone's secret
Cool as a cucumber
Chill, relaxed, easygoing
Cry over spilled milk
Be upset about a small problem
Under the weather
Not feeling well
Count your chickens before they hatch
Make plans for something when it might not actually happen
Comparing apples and oranges
Comparing two things that cannot be easily compared to each other
On the fence
Undecided about something
A rain check
Try to reschedule in the future
Bigger fish to fry
More important problems to figure out
Walking on eggshells
Being careful when interacting with a person so they don't get upset
Cold feet
Nervous about something in the near future
Steal someone's thunder
Take the attention/praise away from someone