Tailgating is all about street food. They have in common the goal to satiate folks who may or may not have a place to sit down.
So, we choose foods that are quick, boldly flavored and easy to tote from tailgate to tailgate. Philly cheesesteak is about as street as it gets, super simple and a proven crowd-pleaser.
To make them properly outdoors, you'll need a cast-iron griddle or skillet. Either is an essential for tailgating. You'll also need a metal spatula with sharp sides. They don't have to be honed, but they can't be square and dull.
The most daunting thing about making your own Philly at home is the meat. It's easy to find but difficult to get butchered the way you need it. At Pat's and Geno's in Philadelphia, they used wafer-thin rib-eye. The steaks are partially frozen then sliced across the top rather than the sides.
To make this work, the beef has to be frozen at least an hour then shaved off across top. If you call your butcher shop ahead, they can do this for you. The folks at Homeland did this for me beautifully.
To do it at home, freeze the beef for an hour. Then, using a very sharp knife or meat slicer, shave layers off the top. With a good meat slicer, you can get that wafer-thin effect. A knife might not get you to perfection, but it'll be close enough to satisfy your fellow fans.
As for the cheese, Cheese Whiz is the choice back East, but that's such a mess it might not be as tailgate-friendly. I used smoked provolone and got a great result. One thing they don't do in Philly is crank the heat, so I added some Serrano chile slices to satisfy my yearn to burn.
Don't forget paper towels; these can be drippy.