Tildes abused.
Surprised? Amused?

   use strict;
   die'TILDE',@~;
   sub CHECK{@~=$~=~m~(.)~g,unshift@~,
   splice@~,2,3;unshift@~,pop@~,*{H},;
   push@~,*{PAR}=>;($~[$#{~}],$~[$#{~}
   +-1])=($~[$#{~}+-1].$/=>$~[$#{~}]);
   for(@{~}){s~.*:~~;s~$~ ~ if$?++%2}}
[download]

Update:Tiny change to fix problem on Windows...

Per request, commented version below. And actually, it was a BrowserUK post last Friday that got me reading perlvar and perlmod, so thanks!