Many people believe it to be the real name of Perl. A notion which is furthered by that appearing at the top of perldoc perl (which is also man perl on Unix systems). OTOH at the bottom of the same man page you'll find that Perl actually stands for Pathologically Eclectic Rubbish Lister.

Those who are familiar with the Perl community will know that both are jokes, and the FAQ is to be trusted on this matter. And will likewise know that anyone who starts talking about PERL lacks significant clues about the language.

For instance I invite you to look for any books on PERL from O'Reilly. You won't find any. They know what they are doing. (Conversely any book on PERL can be safely thrown in the trash unread.)

Cheers,
Ben