# @keys = keys %hash;  # done ONCE
# ($k,$v) = rhe_2(%hash,@keys);

sub rhe_2 (\%\@) {
  my $key;
  do {
    $key = rand @keys
  } until exists $_[0]{$_[1][$key]};
  return ($_[0]{$_[1][$key]}, delete $_[0]{$_[1][$key]});
}