sub printkey {
  my ($self,$key) = @_;
  print "$key : ", $self->{my_hash}->{$key},"}\n";
};

# Now set up the faked object. The real one would be
# with more meat and a constructor I guess.

$self = {};             # $self is an anonymous hash (reference)
$self->{my_hash} = {};   # so is $self->{my_hash}
$self->{my_hash}->{Hello} = "World";

printkey( $self, "Hello" );