$|-- rocks.

[BenGoldberg]

sub _{@_<2&&return print@_;my@a;push@{$a[$|--]},$_ for
@_;_(@$_)for@a};_ split//,"huroP cels,tetah Jen akrr";

[eyepopslikeamosquito]

Running on my machine with Perl 5.16.3 produces:

er,ackrl heP Just another

Changing $|-- to --$| like so:

sub _{@_<2&&return print@_;my@a;push@{$a[--$|]},$_ for
@_;_(@$_)for@a};_ split//,"huroP cels,tetah Jen akrr";

produces the required:

Just another Perl hacker,

See also: Japhy explains where behaviour of --$| is documented.

Update: To further clarify this mysterious "flip-flop" behavior when $| is --'ed, but not when ++'ed, notice that running:

perl -le 'print --$| for 1..5'

produces:

1
0
1
0
1

while running:

perl -le 'print ++$| for 1..5'

produces:

1
1
1
1
1

BTW, this magical --$| flip-flop often produces the shortest Perl golf solutions when you need to flip-flop between two different values in a loop; for example, it was used in Re^2: Mini-Tutorial: Working with Odd/Even Elements and Spending Time on Saving Time [golf].