In CGI.pm, that is a little bit wild. A lot of these sub call self_or_default()..

Uhm.. I was gonna dissect how self_or_default() works.. but... ouch. It hurts. CGI.pm v 3.15 line 442:

sub self_or_default {
    return @_ if defined($_[0]) && (!ref($_[0])) &&($_[0] eq 'CGI');
    unless (defined($_[0]) && 
        (ref($_[0]) eq 'CGI' || UNIVERSAL::isa($_[0],'CGI')) # slightl
+y optimized for common case
        ) {
    $Q = $CGI::DefaultClass->new unless defined($Q);
    unshift(@_,$Q);
    }
    return wantarray ? @_ : $Q;
}
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I mean, I get it.. it sees if the first list element is a ref or not, if it is a ref to 'CGI', it returns the list unchanged. If it is not.. then.. uhm... hmm.