Here is a list of the infamous ZX Spectrum error codes. The most disturbing has to be the R Tape Loading Error message, which you only got moments before a game was supposed to finish loading!! You can use these imaginatively, perhaps as an email signature? I use them for my Google Talk status messages..

• 0 OK, 0:1
  1 NEXT without FOR, 0:1
  2 Variable not found, 0:1
  3 Subscript wrong, 0:1
  4 Out of memory, 0:1
  5 Out of screen, 0:1
  6 Number too big, 0:1
  7 RETURN without GOSUB, 0:1
  8 End of file, 0:1
  9 STOP statement, 0:1
  A Invalid argument, 0:1
  B Integer out of range, 0:1
  C Nonsense in BASIC, 0:1
  D BREAK - CONT repeats, 0:1
  E Out of DATA, 0:1
  F Invalid file name, 0:1
  G No room for line, 0:1
  H STOP in INPUT, 0:1
  I FOR without NEXT, 0:1
  J Invalid I/O device, 0:1
  K Invalid colour, 0:1
  L BREAK into program, 0:1
  M RAMTOP no good, 0:1
  N Statement lost, 0:1
  O Invalid stream, 0:1
  P FN without DEF, 0:1
  Q Parameter error, 0:1
  R Tape loading error, 0:1