<?php

$responseText = array(
    array("hey","hi","hello there"),
    "! ",
    array("i am", "i'm"),
    " ",
    array("good", "great"),
    "! "
);
echo randomResponse($responseText);

function randomResponse($array){
    $result='';
    foreach ($array as $item){
        if (is_array($item)){
            $result.= $item[rand(0, count($item)-1)];
        }else{
            $result.= $item;
        }
    }
    return ($result);
}
?>

hello there! i am great!