A hacker enjoys exploring the details of computers and knows how to stretch their capabilities. Hackers enjoys learning the details of programming systems and loves to stretch their capabilities, as opposed to most users who prefer to learn on the minimum necessary.
Templatesbrowser pirates open source free Wordpress Themes and adds a sneaky piece of code at the end of the file "functions.php" producing links to other sites which is invisible for human readers. They've also removed the author credits from most of the themes.