[cfiggers]

The word "Fu" (pronounced "foo") is a reference to "Kung Fu," a Chinese martial art. It is used colloquially in combination with other words to mean "something someone has to practice to become a skilled expert in." You might see "Google-fu," as in, "skill using search engines to find what you're looking for," or "Spreadsheet-fu," as in, "skill using Microsoft Excel or other spreadsheet programs," or similar things.

In this case, "Command Line Fu" is meant to suggest that the command line is something you can practice to improve your skills with, analogous to a martial art. It's not meant to be pronounced "F you"—though I'm sure you're allowed to continue doing that if you find it amusing!