Bad user interface design:
In the blogging app I have on my phone, if I want to throw away a blog post I have started, I have to click… Save! Then I get another menu with an option to "Discard." "Save" is precisely the opposite of the thing I want to do!
Of course the most famous example of this is Windows, where in several versions, if you want to stop your computer, you have to click a menu that says… "Start"!