JFCL

JFCL /jif'kl/, /jaf'kl/, /j*-fi'kl/ vt., obs.  (alt.
   `jfcl') To cancel or annul something.  "Why don't you jfcl that
   out?"  The fastest do-nothing instruction on older models of the
   PDP-10 happened to be JFCL, which stands for "Jump if Flag set and
   then CLear the flag"; this does something useful, but is a very
   fast no-operation if no flag is specified.  Geoff Goodfellow, one
   of the jargon-1 co-authors, had JFCL on the license plate of his
   BMW for years.  Usage: rare except among old-time PDP-10 hackers.