Code Masturbation

Code Masturbation is an expression I created - I don't know if it has been created already or not - in order to describe the state where people like to write code (programs in C++, Java, Perl, Assembly, etc) independent on what is that piece of software and what it is supposed to do. Programmers sometimes like the feeling of solving tough problems, hacking on existing open source software's like (Snort, Apache, Linux Kernel, etc.) Sometimes writing code is like puzzles solving, where you have to have some imagination in order to find the optimum solution for your problem. So what is your favorite programming language, and is there an open source software that you like hacking on and learn much by reading it and the various techniques in it. For me I like C and like to learn much from Snort and the Linux Kernel.