bug-of-the-month club n.
[from "book-of-the-month club", a time-honored mail-order-marketing technique in the U.S.] A mythical club which users of `sendmail(8)' (the UNIX mail daemon) belong to; this was coined on the Usenet newsgroup comp.security.unix at a time when sendmail security holes, which allowed outside crackers access to the system, were being uncovered at an alarming rate, forcing sysadmins to update very often. Also, more completely, `fatal security bug-of-the-month club'.