How can you not like In-n-Out? Their burgers are how I imagined the Krabby Patty as a kid! It's crazy cheap, customizable and delicious. I personally get a double double with extra toast and extra grilled onions. Add some fries with that and it comes out to $5!
If I'm feeling really hungry I bump up my order to a 3x3 or a 4x4. Sadly, they won't allow you to order more than that :(
Tip: get your French fries well done you'll never regret it