I'm British, and if I didn't already have enough reasons to drink heavily this weekend, I can go ahead and add this video to the list. Look: reality is broken. It's been well and truly Done In and it wasn't even some interdimensional superbomb that did it. Just a bunch of cylinders which are also rectangular prisms when you look at them in the mirror, but when you turn them round they become rectangular prisms which are cylinders in the mirror.
Oh man. Oh jeez.
This is, apparently, the 'ambiguous cylinders' illusion, the creation of Kokichi Sugihar, a professor of engineering at Meiji University in Japan. It's also the second prize winner in 2016's Best Illusion of the Year contest, a community-run competition that aims to remind us that "all perception is illusory to some extent." Well, job done.
Sugihar's work is definitely some of the best in the competition. You may have seen his marvellous creations before, such as these "anti-gravity" slopes:
Like this illusion, the ambiguous cylinders rely on the viewer looking at a structure from a certain angle— in addition to some judiciously placed folds that look like curves when seen back to front. I've still not got my head around exactly how the ambiguous cylinders work, but you can make a simpler version for yourself known as the "ambiguous garage roof illusion" using this cut-out PDF from Sugihar's website. Good luck!