In Rage of Bahamut, you receive a nice bonus when a friend signs up using your referral code.
There's just one small problem. I can't find my referral code! I've checked every screen I could find (even the FAQ), and was unsuccessful. A quick Google search brought back nothing but "lololol use my referral code XD !!1!1" That's considerably unhelpful.
How do I find my referral code?