I
A blessing in disguise
Something good within something bad
Biting off more than you can chew
Taking on something too difficult
Getting a taste of your own medicine
Getting treated the way you have treated others
Letting the cat out of the bag
Telling a secret
The elephant in the room
The subject that no one wants to talk about
A dime a dozen
Something not worth much
By the skin of your teeth
Just barely doing something
Giving the benefit of the doubt
Believing someone without proof
Once in a blue moon
A rare event
Your guess is as good as mine
You don't know
Adding insult to injury
Making a bad situation worse
Don't count your chickens before they hatch
Don't assume something will happen
Giving someone the cold shoulder
Ignoring someone
Piece of cake
Something easy
Throwing caution to the wind
Being reckless or taking a chance
Beating a dead horse
Repeating yourself when the subject has already been discussed too much
Caught between a rock and a hard place
Choosing between two unpleasant things
Going on a wild goose chase
Doing something pointless
Speak of the devil
When someone you are talking about shows up
Every dog has his day
Everybody will get a chance to be the center of attention
Bite the bullet
Face a situation
Feeling under the weather
Being sick
Hitting the nail on the head
Getting something exactly right
The last straw
The final thing that ruins something
Off your rocker
Crazy
Go down in flames
Fail in a big way
A snowball effect
Something that gets bigger and usually worse as it goes
Getting a second wind
Regaining energy after being tired
It's always darkest before the dawn
Things will get worse before they get better
Like riding a bike
Something you never forget how to do