It's been over a year, but there was a simple but otherwise interesting puzzle (especially for newbies) called 'How to become the president' or something on the site.
It was basically like
Which of the following is correct? a) All of the below b) Option C c) None of the above d) All of the above e) All of the above
I don't remember the exact options, but it was similar to what's given above. The solution was to figure out which option could be correct (and all the others incorrect) without causing a contradiction.
The question was well upvoted at the time. It was on-topic and was posted by some high rep user (maybe Gamow or rand al'thor or someone but I'm not sure) so I don't think it's likely the user got deleted. As far as I know, such a question would still be on-topic.
Here's the link I had saved on 28 March 2016