Not exactly a classic obfuscation, it's even clearly formatted, but fun with closures anyway.
This is my first post in this section, so I'm not sure if it's entirely appropriate, please be kind. 
my $p = sub {
    my $n = 2;
    my $g = sub { $n++ };
    sub {
        my $r = $g->();
        $g = sub {
            my ($f, $g) = @_;
            sub {
                while (1) {
                    my $r = $g->();
                    return $r if $r % $f;
                }
            };
          }->($r, $g);
        $r;
    };
}->();

while ((my $n = $p->()) < 500) {
    print "$n\n";
}

[download]
<Reveal this spoiler or all in this thread>
-----
Bill H 
perl -e 'print sub { "Hello @{[shift]}!\n" }->("World")'

[download]

In reply to fun with closure by billh

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