Over a Barrel: helpless, at a disadvantage
Over there.
It is not an idiom, it means your nose is itching.
"Head over heels in love" would be one idiom.
idiom means expression like a page in a book
I believe you mean "hand over fist." It means that money and merchandise are being exchanged very rapidly.
Over there.
This is not an idiom. "It's over" means that it is over, or finished, or done. Whatever "it" refers to has concluded.
If you think about this, you can figure it out. If fish are trapped in a barrel, how could they get away from a gun? It means something is ridiculously easy.
It's not an idiom because it means just what it seems to mean. You should stay on the side of the fence that you are currently on and not climb over.
sit down come over to
I don't know what you mean by "common phrases of," but the idiom "over and above" just means "more than what was agreed upon."
This isn't an idiom because you can figure it out if you look up the word "pins." It is a SLANG term meaning legs, so you knocked him over.
In a difficult situation that causes people to be worried and upset over something or someone
It Means You Have To: DO A BARREL ROLL!
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.