plaid screen n.
[XEROX PARC] A `special effect' that occurs when certain kinds
of memory smashes overwrite
the control blocks or image memory of a bit-mapped display. The
term "salt and pepper" may refer to a different pattern of
similar origin. Though the term as coined at PARC refers to the
result of an error, some of the X demos
induce plaid-screen effects deliberately as a display hack.