nah vs no really

nah

intj
  • here! (when giving something). 

  • No. 

no really

intj
  • no kidding!; is that so? (sometimes used sarcastically in response to the obvious) 

adv
  • really; seriously; used to attempt to introduce a serious point in a less serious conversation 

How often have the words nah and no really occurred in a corpus of books? (source: Google Ngram Viewer )