Ask HN: What's your favorite technical formulation (i.e., the XY problem)?

I chanced upon the XY problem (http://xyproblem.info) and found the concept to be really applicable in my day-to-day when asking and answering questions.

I also recently discovered that my manager had never encountered the word "bikeshedding" before and I've been wondering what other concept or vocabulary is out there that might provide some interesting insight.

Got any favorite terms or interesting formulations you want to share?