Military slang for a severe form of non-judicial peer pressure, manifest physically, as described in A Few Good Men. Lance Corporal Harold Dawson explains it in the stage play and film:
KAFFEE
Harold, what's a
Code Red?
DAWSON
Sir, a Code Red is a disciplinary
engagement.
KAFFEE
What does that mean, exactly?
DAWSON
Sir, a marine falls out of line, it's up
to the men in his unit to get him back on
track.
KAFFEE
What's a garden variety Code Red?
DAWSON
Sir?
KAFFEE
Harold, you say sir and I turn around and
look for my father. Danny--Daniel-- Kaffee.
Garden variety; typical. What's a basic
Code Red?
DAWSON
Sir, a marine has refused to bathe on a
regular basis. The men in his squad would
give him a G.I. shower.
KAFFEE
What's that?
DAWSON
Scrub brushes, brillo pads, steel wool ...
SAM
Beautiful.
A code red can occur in any teamwork situation where one member of the team is not pulling his weight. Another canonical example is the sock party the squad treats Private "Pyle" to in Full Metal Jacket. Even though the term originated in the Marines, it can be found throughout the military, on sports teams, in boarding schools, or anywhere else the fate of the group, regardless of the efforts of the others, can be ruined by one ate up individual.