not know the first thing about

not know the first thing about (someone or something)

To not know anything about someone or something. I don't know the first thing about computers, so you'll have to explain this to me really slowly. What's an attachment again? Geoff wouldn't know the first thing about how to take care of a baby. Thank goodness Frank is there to help babysit. Why do you presume to know what I would or wouldn't do? You don't know the first thing about me!
See also: first, know, not, thing
Farlex Dictionary of Idioms.

not know the first thing about someone or something

Fig. not to know anything about someone or something. I don't know the first thing about flying an airplane. She doesn't know the first thing about John.
See also: first, know, not, thing
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

not know the first thing aˈbout somebody/something

know nothing at all about somebody/something: I don’t know the first thing about Chinese history.
See also: first, know, not, somebody, something, thing
Farlex Partner Idioms Dictionary
See also:
  • closed book, a
  • a closed book
  • before you know it
  • before you know where you are
  • I know
  • know (someone or something) inside out
  • know inside out
  • know somebody/something inside out
  • know someone or something inside out
  • know something/someone inside out
References in periodicals archive
Speaking of personal doctors, only complete morons or clueless civil servants that do not know the first thing about how economics work would have decided to pay these doctors up to 250 grand a year for offering primary care.
Can it be true that "these kids do not know the first thing about what they want to do with their lives" and that "they are totally clueless"?
These were the thoughts of absolute idiots who did not know the first thing about him as a human being.
It means that Suzuki does not know the first thing about environmental economics.
"Frankly," the executive said to me, "we do not know the first thing about these applications and how they apply to us." That is not a good thing.
Up until recently Brett Ratner did not know the first thing about Bollywood movies, but that did not stop the US director being snapped up to helm one.
Unfortunately, many troubled teens who are pregnant or have a baby do not know the first thing about bonding with their child.
'I did not know the first thing about dairying but we knew there was a quicker return,' Dai said.
"I do not know the first thing about moving clubs anyway.
He or she may not know the first thing about the company, but they are willing to learn if well paid.
Of those without a private pension, 60 per cent confessed that they did not know the first thing about pensions - compared to only 45 per cent nationally and 57 per cent complained about sales people not explaining the Economics Editor details clearly enough.
For the better part of six months, the Republic's Monday section has focused on finance issues, typically giving a real-life example of someone who does not know the first thing about a particular financial issue, but it has had its problems, concedes Nicoson.
To be beached is bad if you are a whale [the beach balls boo and blow raspberries] but it is worse if you are a sailor, pestered morning and night by native girls [cheers, whistles] who frequently do not know the first thing about proper dress [catcalls, stomping of feet, showers of confetti; the beach balls cluster around the author and roll him into the sea].'
It could have sent a couple of civil servants for special training if it was unable to find a qualified person for the job in Cyprus, instead of employing a cop that did not know the first thing about running a prison.