devil of it
heck of it
The worst or most unlucky thing about a trouble or accident; the part that is most regrettable.
Andy lost his notebook, and the devil of it was that the notebook contained all his homework for the coming week.
When I had a flat tire, the devil of it was that my spare tire was flat too.
Fun from doing mischief. Used after "for".
The boys carried away Miss White's front gate just for the devil of it.