Understanding the grammar behind ～かよ in 知るかよ and マジかよ etc


I think that
[知るかよ！](http://eow.alc.co.jp/search?q=%E7%9F%A5%E3%82%8B%E3%81%8B%E3%82%88)
means "like I would know!"/"hell, if I know!" and that
[マジかよ！](http://eow.alc.co.jp/%E3%83%9E%E3%82%B8%E3%81%8B%E3%82%88/UTF-8/)
means something like "[are you/is this] for real?"/"seriously?", but is there
an underlying rule behind the ～かよ pattern seen at the end of sentences?

If I was to, for example, say （それを）食べるかよ, what kind of a meaning would it
have?

Can ～かよ also be used as an ordinary question? Does it make a rhetorical
question?




`か` is a sentence final particle that makes a question, and `よ` is a sentence
final particle that adds the subject's attitude. Ignoring the meaning added by
`よ`, which does not affect the core meaning of the sentence, all of the
sentences you have are questions. And in all of your examples, they are
rhetorical questions.

> 知るかよ  
>  literally: 'Do I know/bother about it?'  
>  'I don't know/bother about it!'
>
> まじかよ  
>  literally: 'Is that serious?'  
>  'I can't believe it!'
>
> 食べるかよ  
>  literally: 'Will I eat it?'  
>  'I won't eat it!'
>
> [欧米か!](http://youtu.be/Exbu7SbKg_k)

Note that the addition of `よ` adds subject's attitude, which makes it
difficult to interpret the sentences as literal questions.




`か` is a sentence final particle that makes a question, and `よ` is a sentence
final particle that adds the subject's attitude. Ignoring the meaning added by
`よ`, which does not affect the core meaning of the sentence, all of the
sentences you have are questions. And in all of your examples, they are
rhetorical questions.

> 知るかよ  
>  literally: 'Do I know/bother about it?'  
>  'I don't know/bother about it!'
>
> まじかよ  
>  literally: 'Is that serious?'  
>  'I can't believe it!'
>
> 食べるかよ  
>  literally: 'Will I eat it?'  
>  'I won't eat it!'
>
> [欧米か!](http://youtu.be/Exbu7SbKg_k)

Note that the addition of `よ` adds subject's attitude, which makes it
difficult to interpret the sentences as literal questions.

