genial vs just for the heck of it

genial

adj

  • Friendly and cheerful. 

  • Pleasantly mild and warm. 

  • Marked by genius. 

  • Relating to the chin; genian. 

just for the heck of it

How often have the words genial and just for the heck of it occurred in a corpus of books? (source: Google Ngram Viewer )