# in you declaration at the beginnning of the script
# or in an ini file
%urlsForOccassions{
'fat' => 'weightwatchers.com',
'skinny' => 'muscle.com'
};

# in your script somewhere
$urls .= $urlsForOccassions{'fat'} if $fat;
$urls .= $urlsForOccassions{'skinny'} if $skinny;