UNIX brain damage: n. Something that has to be done to break a network program (typically a mailer) on a non-UNIX system so that it will interoperate with UNIX systems.

:UNIX brain damage: n. Something that has to be done to break a
network program (typically a mailer) on a non-UNIX system so that
it will interoperate with UNIX systems. The hack may qualify as
`UNIX brain damage' if the program conforms to published standards
and the UNIX program in question does not. UNIX brain damage
happens because it is much easier for other (minority) systems to
change their ways to match non-conforming behavior than it is to
change all the hundreds of thousands of UNIX systems out there.

An example of UNIX brain damage is a {kluge} in a mail server to
recognize bare line feed (the UNIX newline) as an equivalent form
to the Internet standard newline, which is a carriage return
followed by a line feed. Such things can make even a hardened
{jock} weep.
-- The AI Hackers Dictionary