Usability for Nerds/Speak the user's language
An old web browser showed this dialog box when opening a pdf file:
It is nice that the program tells me what it is doing while I am waiting for the document, but this message is not very understandable. First, the title "Viewing Location" is confusing: I don't want to view a location, I want to view a document. The text "Spawning External Viewer" is even worse: "Spawning" is something that a fish does. It doesn't make sense here, except to a proficient C programmer. The word "External" is also confusing. The viewer is external from the programmer's point of view, because it is provided by somebody else. But as a user, I don't want to think of who programmed which part of my software, I want to concentrate on the contents of the document I am about to see. Therefore: Speak the user's language and present things from the user's point of view.
You don't have to go to extremes, though. Sometimes users may be offended by a language that sounds too childish, and often there are technical terms that become less comprehensible if you try to "translate" them to everyday language.