my %set = (
    # Populate this somehow.
);

my @keys = keys %set;
my $chosen_key = $keys[ rand @keys ];
my $chosen_value = delete $set{ $chosen_key };

##</code><code>##

my %set;
tie %set, 'DBM::Deep' => { file => 'my_file.db' };
%set = (
    # Populate as desired, nesting arrays and hashes as appropriate.
);

##</code><code>##

my %set;
tie %set, 'DBM::Deep' => { file => 'my_file.db' };

my @keys = keys %set;
my $chosen_key = $keys[ rand @keys ];
my $chosen_value = delete $set{ $chosen_key };

##</code><code>##

my $set = DBM::Deep->new({
    file => 'my_file.db',
});

my @keys = keys %{ $set };
my $chosen_key = $keys[ rand @keys ];
my $chosen_value = delete $set->{ $chosen_key };