have half a notion to (do something)

To have an inclination or intention that is moderate, irresolute, or indefinite (but often one that was motivated by a specific unpleasant experience). My flight home was so terrible, I have half a notion to write a letter to the airline company and complain. We set out on the road with only half a notion as to where we would go! I know you're annoyed and have half a notion to start a fight here, but can we please just get through Thanksgiving dinner in peace?

labor under (something)

To live, function, or operate while believing something or holding an assumption of some kind, especially something that is not or may not be true. We all labored under the assumption that we would be getting paid overtime, so we all nearly quit when we realized that wasn't the case These politicians want us all to labor under the notion that they're our friends, looking out for our interests first and foremost.

not have the faintest (notion)

To have no knowledge or understanding about something. He doesn't have the faintest notion how hard it is to run a business. A: "Do you know where the car keys are?" B: "I don't have the faintest, sorry."

not have the foggiest notion

To have no knowledge or understanding about something. He doesn't have the foggiest notion how hard it is to run a business. A: "Do you know where the car keys are?" B: "I don't have the foggiest notion. Sorry."

pale at the notion of (something)

To be made fearful, nervous, or sickened by thinking about something happening. I know that David pales at the notion of flying in an airplane. We paled at the notion of shutting down the company that our great-great-grandfather created.

run away with the idea

To take a fantastical or unrealistic idea as something that is definitely true or destined to happen. His book appeared on a local bestseller list, and now he's run away with the idea of being a famous author. Local tabloids are running away with the idea of the mayor being a part of a big conspiracy.

run away with the notion

To take a fantastical or unrealistic idea as something that is definitely true or destined to happen. His book appeared on a local bestseller list, and now he's run away with the notion of being a famous author. Local tabloids are running away with the notion of the mayor being a part of a big conspiracy.

the foggiest notion

A basic, vague, or rudimentary knowledge or understanding (about something). Often used in negative constructions. A: "Do you know where the car keys are?" B: "I haven't the foggiest notion. Sorry." Do you have the foggiest notion how much this mistake is going to cost the company? Even though I could speak a little Japanese, I could only pretend to have the foggiest notion what the woman was talking about.

have half a notion to do something

and have half a mind to do something

Fig. to have almost decided to do something, especially something unpleasant. I have half a mind to go off and leave you here. The cook had half a notion to serve cold chicken.

run aˈway with the idea/notion

(spoken) believe something that is not true: Don’t run away with the idea that you’re going to be famous just because you’ve appeared on television once.