How did you hear about us question

I added the how did you hear about us and it is great module. I was just wondering if there is a way to add Friend in the drop down menu and make it work like "Other" where this a text box(es) below to put info in and still have "Other" option below it.

As you can see on mine I just combined Other/Friend but I was wondering what the code would be to make it so when you put a friend or customer referral in you would have to put in both names (first and last) before creating an account.

The reason behind is so if I do have a customer that refers a friend I can send them and the new customer a personal coupon for them.

Thank you
Jay

https://www.krazykingsoftoys.com/cart/

Could you just edit the language file to put some text in brackets after the question? Perhaps (if referred by a friend, please provide friend's first and last name so that we may send your friend a discount coupon) or something of that nature.