mouse droppings

( n.)

   [MS-DOS]  Pixels (usually single) that are not properly restored when
   the  mouse  pointer  moves  away  from  a  particular location on the
   screen,  producing  the  appearance  that  the mouse pointer has left
   droppings behind. The major causes for this problem are programs that
   write  to  the  screen  memory  corresponding  to the mouse pointer's
   current  location  without  hiding the mouse pointer first, and mouse
   drivers that do not quite support the graphics mode in use.

[glossary]
[Reference(s) to this entry by made by: {magic cookie}]