Common Idioms Quiz! (North American English)

What does it mean when someone says they are "on top of the world"? 

Which one is a real idiom, meaning "you're joking around, lying to me"? 

Fill in the blank: Kate is such a dreamer. She's never thinking about where she is or what she's doing. Her head is in the ________!

When no one is talking about an obvious problem, we call it an __________ in the room.

When it _____, it ________. This means bad things always happen together. 

What word goes in both of these blanks?
You're on thin ___. Don't say the wrong thing! 
You need to break the ___! Tell her a joke or something!

They tried to have a surprise party for her, but her brother spilled the _______. It was ruined!

What do you "read between" to find unwritten/unspoken information?