"In touch" simply means to contact someone in some way - by calling them or writing or emailing or even going for a physical visit.
To stay in touch is to continue to write/text/call or otherwise stay in contact with someone.
Someone who has the midas touch has a knack for making money.
I'll get in touch with you later and we'll meet for dinner.
Don't call me, I'll call you
RFP is not an idiom. It's an abbreviation.
It's not really an idiom. It means "what are you thinking about."
It is not an idiom, it means your nose is itching.
idiom means expression like a page in a book
It's not an idiom. It means the tip of your nostril.
"Sieve" is not an idiom. See the related link.
This is not an idiom. It is a measurement. $100,000 is how you write it in numbers.
Simply its mean a bully.