Get IN-N-Out's secret menu (search from the internet) and use from that next time your really hungry. Will not be on the official IN-N-OUT web site.
Suggest a Animal Style burger, for a start. All this even applies to fries and shakes. Any way you what it, any style. One thing about their fries is you have to eat them right away. If you take them home to eat, never quite the same. Even have root beer floats.
BB'ers & lifters have know about this for years. Very popular with football players. IN-N-OUT's burgers really go great with beer, made for each other.