Working on one of the major programming languages surely is a lot of fun but sometimes very weird things happen. In these moments Python stops behaving like Python and you enter a new dimension where everything is possible. And debugging what's going on in this new world of weirdness is quite a daunting task given the size of the CPython codebase. In this talk you will learn some of the most obscure, mind-bending and difficult bugs that we faced when developing CPython and how we solve them. You will also learn all the advanced tips and tricks that we used to slay these dragons so you can fight similar monsters in your own codebases or if you want to contribute to CPython itself!