Clam up

To " Clam up" means to be quiet or stopped talking. The idea is the clam often shuts itself whenever encountered danger of any form, therefore, it has some connotation to brevity itself. This idiom was often used to describe a person who was silent and was more of a fun metaphor than a rude commentary( Such as shut up). From what I was told, this idiom was common among many english-speaking societies and I personally find this idiom interesting. Just though it would be worthy to share. Right now I have more outbreaking news. WHat I hold in my hands is precious gold, something irreplaceable and just happened to fall out of the blue sky (not literally).  I can bet that you are dying of curiosity, and I will not keep you waiting for long. What I have is " The Diary of a Wimpy Kid"'s newest book called " Cabin Fever". I cannot wait to start flipping the pages. Thank you, Vivian :)