Double strikeout

This is modified from the double underline macro of ulem (note that \MakeRobust is also defined by that package):

\def\dout{\bgroup
 \markoverwith{\lower-0.2ex\hbox
 {\kern-.03em\vbox{\hrule width.2em\kern0.45ex\hrule}\kern-.03em}}%
 \ULon}
\MakeRobust\dout

and seems to work quite well: