[murl]

Piss jar

I can't believe I missed this. You guys might scoff at this, but you will forgive your past self if you keep an empty bottle in your car, preferably something with a large lid like an empty Gatorade to give you some space. If you are not a dude, I suggest something with a wider opening in case the backyard sprinkler thing happens. 

ALSO...this might be extreme, but if you are a true car-prepper, add a large poop sock to your 'carsenal' because I promise you EVERYONE will have a major poop scare on a long road trip at one point in their life. The poop sock can collect and also wipe, which you can roll up and toss. If you are not a degenerate and don't want to litter, carry a few plastic bags you can wrap it up in.

I promise you guys, it will happen. Nobody expects it to happen to them, but it will. You will eat terrible food and go on a long drive at some point in your life, and you will look back on this post and thank me.