Changing login error message (wp-admin)

custom_error_msgs

<?php
// Insert into your functions.php and have fun creating login error msgs
function guwp_error_msgs() { 
    // insert how many msgs you want as an array item. it will be shown randomly 
    $custom_error_msgs = array(
        '<strong>YOU</strong> SHALL NOT PASS!',
        '<strong>HEY!</strong> GET OUT OF HERE!',
    );
    // get random array item to show
    return $custom_error_msgs[array_rand($custom_error_msgs)];;
}
add_filter( 'login_errors', 'guwp_error_msgs' );
?>