The xkcd is a joke that if you want to do anything in Linux, just put in a sudo. The blog post is a Makefile content that you will enable you to type it in the terminal with the output as the comic.

What you should try is to create a file named `Makefile`, put in the content in the blog post. Then open the terminal and type `make me a sandwich` then `sudo make me a sandwich` and see the result.

There's an xkcd comic where the protag tells someone to make them a sandwich. They respond, "no, make one yourself." The protag then says "sudo make me a sandwich" and they respond "Okay". If you've ever set anything up in unix from the command line, you've run a command only to realize you need to run it as a super user (sudo). The post is scripting that let's you run "make me a sandwich" and "sudo make me a sandwich" in command line, just like the xkcd comic. It's not much of a joke, more of a novelty.