Less an obfuscation than an interesting obfuscatory trick that should either succeed or fail gracefully, but instead, on perl v5.6.1, i686-pc-linux-gnu, it segmentation faults and dumps core. It seems to have something to do with pushing an eval context and never popping it, according to re 'debug'.

Update: Posted wrong code at first. Fixed.

#!/usr/bin/perl
use strict;
use warnings;
use re 'debug';

my (@a, $a);

@a = qw(Obfuscatus Re(ge)x);

$_ = 'hello, world!';
BAR: 0;
m((??{goto FOO}))g;
   
FOO:
$a = shift @a;                         ### Fails here
$a and s(\G(.* )[^ ]+)($1$a) and do
{ pos = pos() + 1; goto BAR };
print "$_\n";
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