Between the three Aperiodical editors (myself, Christian Lawson-Perfect and Peter Rowlett), there’s a developing tradition of excellent mathematical gift-giving. This year, Christian has excelled himself by designing and creating a brilliant mathematical hoodie, which features a meme about an in-joke (and who can resist either a meme or an in-joke?)

A few years ago, I produced a YouTube video about the pseudorhombicuboctahedron – a 3D solid made of equilateral triangles and squares, which has the property that each of its vertices is identical (having three squares and a triangle meeting at each point). The problem with the pseudorhombicuboctahedron is that, even though this satisfies many people’s definition of an Archimedean solid, it isn’t considered to be one of the 13 Archimedean solids.

The elongated square gyrobicupola, as it’s known to its friends, is denied admission on the basis that it doesn’t also possess a global isometry – it’s got a weird twist in it, which I think only makes it cooler, but Archimedes didn’t seem to consider it worth including (or: didn’t know it existed) when he compiled his canonical list. Either way, I’ve shouted about it enough, including on our Mathematical Objects podcast about the pseudorhombicuboctahedron (and it even got a mention from Matt Parker in a video a few months back).

A recent new meme format, also themed around specifically excluding one example from a set, is the ‘Thank You… NOT YOU‘ meme, some examples of which are shown below, so you can get the idea.

Faced with this new development in memeing, and a niche mathematical in-joke, CL-P heroically combined the two to produce a truly wonderful (for those in the know, or prepared to listen to a short explanation) graphic.

This was duly printed on a hoodie and sent as a gift to me, and I’ve been wearing it almost all of the time when I’m not directly required to look presentable and not have a meme on my shirt ever since.

And if you were wondering whether it’s possible for you to look as cool as me (or this person in an autogenerated promotional image, right), the answer is yes! The ‘The pseudorhombicuboctahedron is not an Archimedean solid’ design has been added to the Aperiodical’s RedBubble shop, where you can order it printed onto a variety of clothes, accessories and homewares.

There are also several other Aperiodical designs on there now that can be made into objects for a fee – including this lovely throw cushion printed with an image of two old dudes contemplating an octahedron from an old Henry Dudeney book, which was also sent to us by CL-P and matches our home decor remarkably well. Fill your boots!