This modified version avoids proper nouns and applies some meter to the verses by counting (half-)syllables.

#!/usr/bin/perl
#ode to a random number v0.2
open my $dict, "</usr/share/dict/words"
or open my $dict, "</usr/share/lib/dict/words" ;
my @words = <$dict>;
my $count = 70*rand();
{ use integer; $count /= 1; }
my $syllables = 0;

for ( 'a', 'e', 'i', 'o', 'u' ) {
    $vowel{ $_ } = 1;
}

for ( 0..$count ) {
    my $ptr;
    my $thissyll;
    do {
        $ptr = rand() * $#words;
        $thissyll = Syllables( $words[$ptr] );
    } until ( $words[$ptr] eq lc( $words[$ptr] )
              and ((20-$syllables-$thissyll) >= 0 ));
    $syllables += $thissyll;

    chomp $words[$ptr];
    unless( $_ ) {
        $words[ $ptr ] =~ /^(.)(.*)$/;
        my $b = uc( $1 );
        $words[$ptr ] = $b . $2;
    }
    if ( $_ < $count ) {
        print $words[$ptr];
        if ( $syllables >= 20 ) {
            print ";\n";
            $syllables = 0;
        }
        else { print ' '; }
    }
    else {
        print $words[$ptr] . ".\n";
    }
}

sub Syllables {
    my $word = shift;
    chomp $word;
    my $lv = 0;
    my $tv;
    my $syll = 0;
    for my $letter( split '', $word ) {
        $tv = $vowel{ $letter };
        ( $tv == $lv ) or $syll++;
        $lv = $tv;
    }
    return $syll;
}
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First output:

Policeman nereid spokesman trendy;
fragmentary magnetite enunciate;
dyspeptic lean recombinant decile myrtle;
afterlife disdain derange redneck;
devious attentive condemnatory nymph 2nd sou;
astigmatism shine zagging sage auk;
incentive tattle woodrow deposit;
boolean stagnant setback cull objet dust;
elysian stuck temper freethink octile my yea;
trauma endogamous cohesive hay;
applejack ramp squalid beatitude a;
byline novitiate noun rawhide guile;
cutset pig sundown puff stablemen max;
meteoritic sword dose epiphyseal vie;
ceremony.
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