From a webpage about the book Higher Order Perl

 The other reason that the cover pictures are significant is that since my original goal in writing the programs was to impress my girlfriend, the cover pictures are therefore part of the output of the most successful Perl programs I’ve ever written. I wish all my programs achieved their design goals so spectacularly.

I tried that once - I had my wife write the last sentence of my first book for me. I thought it would be a great way to share the accomplishment with her.   Instead, she criticized my sentence structure and completely ruined the moment.  Alas