What the fuck is a monad?
Or: functor? I 'ardly know 'er!
Monads are difficult to explain without sounding either patronizing or condescending: I would sound patronizing if I came up with some facile analogy and I would be condescending to describe it categorically.
Instead, I'll frame a problem and piece-by-piece solve the problem with what will turn out to be a monad.