It means secretly.
Nothing that I have ever heard. "Under the weather" is an idiom, but there's no anger in the phrase.
judging someone by the way they look, not who they are as a person
Went under is used to mean they have failed, as in drowning. A business that went under is one that has closed or gone bankrupt.
Er ... what? Are you asking what "under one's wing" means? Here's a link.
It depends on what the rest of the phrase said. "Everything under the sun" is a figurative way of saying "everything," while "under the sun" alone would mean out in the sunlight.
The idiom, "You must have been under a rock" means that you must have been away, in hiding or had no contact with civilization to miss this big eventFor example 'You didn't hear about him? You must have been living under a rock to miss that!'
Having already been judged badly, and having to get out from under the cloud before proceeding.to be under suspicion or in disgrace; to be in disfavor.
You can't show me anything that I haven't seen already.?
"On the outs" IS an idiom! Many colorful expressions cover the subject of fallen out lovers, among them Splitsville and Pffft.
It's not really an idiom. It means "what are you thinking about."
RFP is not an idiom. It's an abbreviation.
It is not an idiom, it means your nose is itching.