Someone got Linux running inside a PDF file, because its users are something else

Every so often, we see a wave of activity around cramming something that shouldn't be running in a specific document or app into said document or app. If you (like myself) had the naive thought that PDF files were static, boring documents that can't do things like, I don't know, play Tetris or something, then boy, do we have news for you. Someone has taken PDF tinkering to the next level and got Linux running within a document, and you can give it a spin if you don't believe me.