Add SKU to Woocommerce Order Title

I've added this code to my Wordpress website: [login to view URL] It basically allows the customer to order a free sample for any product. The code works like this currently: 1. There's one Woocommerce product created called "Free Sample" 2. The custom PHP code adds a "Request a Free Sample" button to each product page. 3. When the user clicks "Request a Free Sample" when viewing a normal product, the "Free sample" product is added to the cart with the CURRENT product name appended to the "Free Sample" title. 3. When the order is placed, the admin sees this under the order information: Free sample for: (Product Name) The task here is to add the SKU to the free sample order meta. So it would say "Free sample for: (Product Name) - SKU"