It was a phrase. "Hold on to your hat, there is going to be a bumpy road ahead"!
It means you refrained from saying something
"Asshat" is an American idiom meaning obnoxious idiot. It alludes to a person having their head up their buttocks and wearing it as a hat.
"To be" is not an idiom - it's a verb.
Condescending or supercilious toward
You had to take your hat off to him based on his success.
Pest is not an idiom. It's a word.
The idiom "apple shiner" means the teacher's pet.
The meaning of the idiom in the pink of health means being in good health.
Eat your hat: a statement made when you are positive that something will happen, as in "I'll eat my hat if our team loses this game."
Hold on can be an idiom meaning 'wait a moment', or 'stop'. Assuming that it is:Hold on, I'm about to finish my assignment!Wait, hold on for a second- I just got an e-mail.Assuming that you literally mean 'hold on':Hold on, I won't let you fall!
They mean that your expectations may be unrealistic or unlikely. They are telling you not to hold your breath, but to move on happily.
John loved to dance and would do so at the drop of a hat.