for (1..4) {
   my %picked;

   (my $text_new = $text_orig) =~ s/[A-Z]{3,}/
      # We need more @products or a better algorithm if this executes.
      undef %picked if keys(%picked) > int(@products/2);

      my $pick;
      do { $pick = int(rand(@products)); } while not $picked{$pick};
      $picked{$pick} = 1;
      $products[$pick]
   /eg;

   print($text_new);
}