That's actually the point of the article. There used to be a cottage industry in using real-world analogies to explain Monads. I'm not sure whether it started

That's actually the point of the article. There used to be a cottage industry in using real-world analogies to explain Monads. I'm not sure whether it started as an in-joke or not, but the most outlandish metaphor among others involved burritos (other metaphors out there that really did exist: assembly lines, toxic waste handling, and space suits). So now burritos are an in-joke among Haskell programmers, sort of a whimsical shibboleth. Check my other post in this thread for what I hope is a more accessible explanation of Monads. They're a very abstract thing, so there's no concrete metaphors to be had, just a common thread of piping values through "contextful" functions.