Why not?

why not

1. Why is that not the case? What is the reason for your negative statement? A: "George has decided he's not going to join." B: "Why not?" A: "I don't like coconut." B: "Why not? Because of the texture?"
2. Yes, because there is no good reason to say no. A: "Would you like another glass of wine?" B: "Sure, why not?"
See also: not, why
Farlex Dictionary of Idioms.

Why not?

 
1. Lit. Please explain your negative answer. Mother: No, you can't. Mary: Why not? Sue: Could I have another piece of cake? Mary: No. Sue: Why not? Mary: I want it.
2. . Inf. I cannot think of a reason not to, so yes. Bob: You want to go to see a movie next Friday? Jane: Why not? Fred: Do you feel like wandering over to the bowling alley? Tom: Why not?
See also: why
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

ˌwhy ˈnot?

(informal) used to make a suggestion, or agree to a suggestion: ‘Why not go and see a movie?’ ‘OK.’ ‘Let’s go and see a movie.’ ‘OK, why not?’
See also: why
Farlex Partner Idioms Dictionary
See also:
  • (I) hope not
  • hope not
  • not for a second
  • not for a minute
  • not for a moment
  • aint
  • ain't
  • not for a/one minute/moment/second/instant
  • not for a instant
  • not by any means
References in periodicals archive
The inaugural "Why Not?? Comedy Show" was created to become a staple event in Oklahoma, kicking off the Thunder's NBA season.
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Aberdeen have no reason not to believe they can got o Celtic Park and win todayirteen games unbeaten, 35 points from 39, 11 clean sheets why not? Aberdeen have no reason not to believe they can got o Celtic Park and win today.
Why not? A line or two that celebrates the joy you felt when you
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Why or why not? Will you be getting the PS4 or the Xbox One?
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Hell, why not? It's the spring of 2006, we haven't had the midterm elections, we don't know how things are going to work out in Iraq--anything can happen.
MOVE BACK IN WITH YOUR FOLKS: Why not? Think of all the dudes that never even move out of their parent's house in the first place.
For had I whispered "Why you?" she would have responded "Why not?"
In Why Not? (Harvard Business School Publishing), the authors Barry Nalebuff and Ian Ayres bombard us with a series of new ideas on how to put everyday activities into practice.
And they provide some solid lessons in Why Not?: How to Use Everyday Ingenuity to Solve Problems Big and Small (Harvard Business School Press; $27.50).
THE artistic Spaniards love their fancy paint jobs and why not? Look how Nissan of Spain have transformed this otherwise boring white Nissan Micra, left.