Like toolic's (except that he beat me to most of it) but I figured your $string was not intended to be a no-op:

#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;
my %wtf;

my $string = "test me";

my %hash = parse($string);

print "Dumping from main:\n";
print Dumper %wtf;
print "------\n\n";
print "dumping hash\n";
print Dumper %hash;

print "__________\n\n";
print "\n printing hash:\n";
print Dumper(%hash);
print ref %hash, "\n";

sub parse {
    my @a = split (/ /,"test me");
    my %b = (
    "one" => "1",
    "two" => "2",
    "three" => "3",
    );
    my $c = "c";

    %wtf = (
       aaa => \@a,
       bbbb => \%b,
       ccccc => $c,
       );

return %wtf;
}
[download]

Output:

perl 706464.pl
Dumping from main:
$VAR1 = 'ccccc';
$VAR2 = 'c';
$VAR3 = 'bbbb';
$VAR4 = {
          'three' => '3',
          'one' => '1',
          'two' => '2'
        };
$VAR5 = 'aaa';
$VAR6 = [
          'test',
          'me'
        ];
------

dumping hash
$VAR1 = 'ccccc';
$VAR2 = 'c';
$VAR3 = 'bbbb';
$VAR4 = {
          'three' => '3',
          'one' => '1',
          'two' => '2'
        };
$VAR5 = 'aaa';
$VAR6 = [
          'test',
          'me'
        ];
__________


 printing hash:
$VAR1 = 'ccccc';
$VAR2 = 'c';
$VAR3 = 'bbbb';
$VAR4 = {
          'three' => '3',
          'one' => '1',
          'two' => '2'
        };
$VAR5 = 'aaa';
$VAR6 = [
          'test',
          'me'
        ];
[download]