hadn

(one) hasn't the foggiest

To have no knowledge or understanding whatsoever about something. I'm trying to find my car keys, but I just haven't the foggiest where they could be. A: "Did you have any idea what would happen?" B: "I hadn't the foggiest, I swear!"
See also: foggy

hadn't oughta

slang Should not have. I hadn't oughta stayed out so late last night—I'm exhausted. Sarah is pissed off! You really hadn't oughta said that to her.
See also: oughta

have not heard the half of it

To know only a small part of how bad something is, but without understanding the complete situation; to underestimate or be uninformed about how bad a situation really is. Our bosses think that this is a major setback, but they haven't heard the half of it. We're months, not weeks, behind schedule! A: "I heard you and Terry were going through a tough time." B: "Oh, you haven't heard the half of it."
See also: half, have, hear, not, of

if it hadn't been for (someone or something)

If someone or something hadn't helped, intervened, or affected the situation in some way. The phrase is always followed by an explanation of how things would have turned out differently without someone or something. If it hadn't been for those quick-thinking bystanders, I wouldn't be alive today. If it hadn't been for those meddling kids, we would have gotten away with it.
See also: been, if

not have the foggiest idea

To have no knowledge or understanding about something. He does not have the foggiest idea how hard it is to run a business. I do not have the foggiest idea where I left my car keys.
See also: foggy, have, idea, not

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."
See also: foggy, have, not, notion

not know enough to come in out of the rain

To not have very much intelligence or common sense, especially when facing or presented with a difficult situation. I'm not surprised his latest business venture failed too—that fool doesn't know enough to come in out of the rain. Cut him some slack, Jim. You didn't know enough to come in out of the rain when you were his age, either.
See also: come, enough, know, not, of, out, rain
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

hadn't oughta

Inf. should not have. You hadn't oughta teased me like that. I know I hadn't oughta stolen that candy.
See also: oughta

not know enough to come in out of the rain

Fig. to be very stupid. Bob is so stupid he doesn't know enough to come in out of the rain. You can't expect very much from somebody who doesn't know enough to come in out of the rain.
See also: come, enough, know, not, of, out, rain
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.

not have the foggiest idea

or

not have the foggiest

INFORMAL
COMMON If you do not have the foggiest idea or do not have the foggiest, you do not know anything at all about something. I did not have the foggiest idea what he meant. `How often does it need to be changed?' — `Haven't the foggiest.'
See also: foggy, have, idea, not
Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012
See also:
References in classic literature ?
"Dat bloke was a dandy," said Pete, in conclusion, "but he hadn' oughta made no trouble.
It hadn't ever come home to me before, what this thing was that I was doing.
"Pooty soon I'll be a-shout'n' for joy, en I'll say, it's all on accounts o' Huck; I's a free man, en I couldn't ever ben free ef it hadn' ben for Huck; Huck done it.
I tried for a second or two to brace up and out with it, but I warn't man enough -- hadn't the spunk of a rabbit.
'I'm sooary I ha spok'n on 't,' said Stephen, 'I ought t' hadn in my mind as I might touch a sore place.
One netizen wondered if Prince Charles would have still married Camilla even if Princess Diana were still alive and hadn't lost her title.
Party Chairman Bilawal Bhutto Zardari has stated that PPP had faced dictatorship and terrorism but hadn? taken any U-turns like PTI.He stated this while addressing a function of Sindhi Cultural Day.
In 2011, the ex-Foreign Minister joined PTI but parted ways during 2013 reasoning that Imran Khan hadn t kept the promise with him.
It does feel a little bit weird now because it was such a long time ago, but it's quite strange that before doing Blind Date I hadn''t really expressed an interest in television, I'd never actually thought it was something that could feasibly happen.
2008 League Cup Final - Everton 1-0 Arsenal THE Gunners hadn''t been beaten domestically in almost two years and few had given the Blues hope.
I''ve memories of drinking ridiculous volumes of ridiculous drinks in ridiculous ways (snorting vodka anyone?) or would have if I hadn''t done it.
7 What did the Barbie Doll get in 2000, which it hadn''t had before?
If only I hadn''t written on my hand and slept on it.
And while Tina is forced to bond with him in ways she hadn''t expected, she''s also getting closer to Tommy again as well.