If we are talking big chain fast food it's In-N-Out, hands down. And they have waaaaaaay better fries then McD's, IMO. (Of course I won't go to McD's after i got violently ill the last time I ate there.)
If it's a small/non-chain then probably The Hat. Not sure if they are outside of Cali, but they have awsome pastrami cheesburgers. Oh man, you get a double pastrami cheeseburger and then ask for avocado and bacon added to it. Have that with some wet fries and a Dr. Pepper and life will be so complete that you won't mind the heart attack that will kill you 10 minutes later.
If it's a small/non-chain then probably The Hat. Not sure if they are outside of Cali, but they have awsome pastrami cheesburgers. Oh man, you get a double pastrami cheeseburger and then ask for avocado and bacon added to it. Have that with some wet fries and a Dr. Pepper and life will be so complete that you won't mind the heart attack that will kill you 10 minutes later.