Rory Parle has posted a puzzle which is the kind of thing a number of people who still read this would be interested in, so:
You have in front of you one of those tables you get in Asia restaurants with the rotating centre—what one of our product managers described as a lazy susan, though I’ve never heard that phrase from anyone else. Picture the restaurant from the beginning of Indiana Jones and the Temple of Doom if you really want to set the scene.
On the table are four glasses, each of which is either standing upright or turned upside down. They’re evenly spaced around the table, in a square. You sit at the table blindfolded. Your aim is to turn the glasses such that they are either all upright or all upside down, subject to the following rules:
now go read the rest of the puzzle