#!/usr/bin/perl
use strict;
use warnings;

use DB_File;
my %hash;
my $tied = tie %hash, 'DB_File', "garbagefile";
$hash{foo} = "bar";
print STDERR $tied->FETCH('foo') . "\n"; 
$$tied--;
print STDERR $tied->FETCH('foo') . "\n"; 

__END__

Outputs:

slothbear:~/perltest marvin$ perl ptrobj_segfault.plx 
bar
Bus error
slothbear:~/perltest marvin$