Congratulations! You've done something very clever! Your out of the box thinking has now retarded the development process!
Oh? You're not sure what I'm talking about? Well remember that thing you did? I'm pretty sure you knew that it felt like a hack when you wrote it but then you quickly convinced yourself that you'd invented something insanely brilliant. Well, it wasn't. It was a hack. And now, somewhere, kittens are dying.
Yes, I know the compiler didn't complain but that doesn't technically make it valid code. Just because you can use operator overloading to concatenate files doesn't mean you should. Oh yeah and remember that non-standard event signature you implemented to save time? Well it turns out that we really did need event arguments and proper error handling, so now Jimmy, who is replacing you btw, is going to have to rewrite it. kthxbai.
It's not clever, or agile or lean or whatever it is you think it is. It's sloppy. I can't think of a profession where cutting corners is okay.
So before you start bringing the protestors to your aid that "retarded" is an offensive word, I mean it for the true sense, for slowing down the development or progress of action, process, etc. Anytime a developer squints and wonders what was going through your mind -- you've failed to help others understand your code. And know what the funny thing is? It doesn't take much more to do it right. It might take an few extra seconds to put xml comments at the top of the method, or a few extra minutes to write a unit test. If you consider that we spend more time trying to understand code than writing it, it really makes sense to ensure that code remains consistent.
For me, clever is often synonymous with stupid. Everyone's entitled to a few embarrassing "clever" moments a year as long as the own up to it. Going full in and swearing by it, well, …sometimes you come back empty handed.