#!/usr/bin/perl -w
# the above (-w) turns on warnings, Windows ignores the path!!

use strict;
use Data::Dumper;

my $hashref={}; #a reference to anon hash table

$hashref->{username} = 'NOOoooooo!';

print "User Name:  $hashref->{username}\n";

test( $hashref );

sub test  
{
    my $reference = shift;
    my $test = "Pigsy's Perfect Ten";
    $reference->{username} = $test;
    print "Inside Sub Test test\'s value is: $reference->{username}\n";
    $reference->{'accountid'} = '234piggy';
}
print "User Name:  $hashref->{username}\n";
print "Account ID: $hashref->{'accountid'}\n";

__END__
Prints:
User Name:  NOOoooooo!
Inside Sub Test test's value is: Pigsy's Perfect Ten
User Name:  Pigsy's Perfect Ten
Account ID: 234piggy