The other day, while reading my timeline in twitter I found an interesting link from Katrina Owen that participates in Ruby Rogues. The website is http://exercism.io/. And like it says in their landing page, this really exercise your brain, not only assess you with funny and creative examples using different programming languages, but also you receive feedback upon your code once you submit it.
So, are you still thinking that you know more than any other programmer in the world? Give it a try!
Install the gem:
$ gem install exercism
Create a folder where you will work on those exercises
$ cd projects/exercises # or whatever
$ exercism login