$_='print"\$_=\47$_\47;eval"';eval

If you enjoy self-generating, self-replicating or self-modifying code as much as me,
you can have a look here. The exponential more-perl engine is probably
never executed in the 5th generation, except you have plenty of RAM
and CPU power (e.g. you work for google:).
All samples you can download execute the same code at the end, even though
they need to un-nest and reorder the instructions until original code,
including comments, is reached.