$users = array('john', 'jane', 'tim', 'alex');
$lucky_winner = array_rand($users);
echo $lucky_winner;
// alex

users = [ 'john', 'jane', 'tim', 'alex' ];
lucky_winner = users[rand(users.length)];
puts lucky_winner;
# => alex

$a = array('a', 'b', 'c', 'd');
shuffle($a);
print_r($a);
/*
Array (
	[0] => d
	[1] => b
	[2] => c
	[3] => a
)
*/

a = [ "a", "b", "c", "d" ];
puts a.sort_by{ rand };
# => ["d", "b", "c", "a"]