the Head First books are very clever. However, one of the images used is really objectionable. This is the image on pg. 1 of the PHP & My SQL book. I know that it is also in the Java book.
There's nothing remotely humorous about this image and just because it's 'vintage' doesn't make it OK. It should be common sense that this is distasteful, don't you think? The fact that the people responsible for the book/s didn't think so, really reflects poorly on O'Reilly. My two cents.