To honor Easter, I’ve decided to put this little tidbit of information up. These are PHP easter eggs.  I had no idea these existed until I was running a security scan using Detectify.  This information can be considered to be a vulnerability since it could be used to obtain specific server information/versions and use that version as a reference to look up exploits against PHP, the server, etc.
You can use these by visiting your site, or another site, and using them in the URI:

http://www.example.com/?=PHPB8B5F2A0-3C92-11d3-A3A9-4C7B08C10000

PHP Credits (phpinfo):
PHPB8B5F2A0-3C92-11d3-A3A9-4C7B08C10000
PHP Logo:
PHPE9568F34-D428-11d2-A769-00AA001ACF42
Zend Logo:
PHPE9568F35-D428-11d2-A769-00AA001ACF42
Easter Egg (animals and a guy):
PHPE9568F36-D428-11d2-A769-00AA001ACF42