It is a worm that usually comes as BADASS.EXE program attachment in an email. The size of] this attached program file is 24,576 bytes. The email message has a jumbled looking subject line and a message body in Dutch:-

Dit is wel grappig! :-)

The worm displays an insulting 
                    message box with un-click-able NO button. In the background, 
                    it uses Microsoft Outlook to send a copy of itself to people 
                    in the MS Outlook address book.