Here's a neat use of Perl's aliasing of @_.

#! perl -slw
use strict;

## Shuffle an array in place;
sub shuffle {
    my $ref = @_ == 1 ? $_[ 0 ] : \@_;
    my $n = @$ref;
    for( 0 .. $#$ref ) {
        my $p = $_ + rand( $n-- );
        my $t = $ref->[ $p ];
        $ref->[ $p ] = $ref->[ $_ ];
        $ref->[ $_ ] = $t;
    }
    return unless defined wantarray;
    return wantarray ? @{ $ref } : $ref;
}

my @a = 'a' .. 'c';
my @b = 1 .. 4;
my @c = 'A' .. 'E';

shuffle( @a, @b, @c );;
print "A:= [ @a ]\nB:= [ @b ]\nC:= [ @c ]";

__END__
c:\test>junk8
A:= [ c b D ]
B:= [ 4 A 3 B ]
C:= [ E 2 a 1 C ]
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Notice how after the shuffle, the elements of the arrays have been intermixed in the 3 arrays, but each knows how big it is. This is because @_ gets aliased to the elements of all 3 arrays.

Thus, by shuffling @_ within the sub, we are shuffling the elements of all 3 arrays at the same time.