Meaning: complicated, ridiculous, or unbelievable story. A story or explanation which is obviously not true

Example:
1.- She started to tell some cock and bull story to the police officers about how she found a huge bag containing 5 pounds of gold.
2.- When I asked him about his progress he tried to give me a cock and bull story, but did not care to hear what he said.

Meaning: very happy. Extremely cheerful.

Example:
1.- She's been on cloud nine since she heard the news of her engagement.
2.- I felt like I was on cloud 9 when she said that she I loves me a lot.

Meaning: go public about something private or hidden. To express an extremely private matter in public

Example:
1.- He was in his late teens when he came out of the closet.
2.- She came out of the closet quite late herself but now speaks about how others should make the move much sooner in their lives.

Meaning: something that one knows or understands nothing about.

Example:
I'm afraid that this new physics formula will always be a closed book to me.