Lol, we really did spend 40 minutes or more debating fast food royalty. Is a king better than a queen? Would we all have to smell the 12yo's farts if he had ice cream? Did DQ have onion rings? The king did. Etc. (The 12yo swore that ice cream would not make him fart and that he'd give us notice if he had to. Then he didn't. When we yelled at him, he managed to choke out, "I lied!" In between his heaving laughter.)
In the car, no conversation is too boring or stupid.
We also spent a lot of time determining how much longer we had to the next Woo (state border).
There is place we pass driving on 77 in North Carolina where there are a bunch of pretty buildings on water. On warm days, people are often out on the water. We always talked about it. One time we had to stop for gas there late at night and we saw a Lady of the Evening at the gas station. Sis said that was why it was so nice there...they were all owned by wealthy whores. Ever after, that area has been referred to as "the whores", lol. It marks our half-way point.
We have names for many things we pass. Sis couldn't pronounce Sesquicentennial and called it Sasquatch Centennial.
So, a big part of the drive is passing stuff we know. Also discussing where we should stop overnight.
Honestly...no matter how long the drive is...if you do it with your loved ones, there is a lot of fun to be had in between the "He's on my side!" crap.
In our car that discussion would go something like "it made her fart!!!"---"No, I just passed gas!" They were scolded at school recently for not using the term "passed gas," and while they are careful to use the polite term around said teacher...in all other areas it's just funny since now they have another word/saying for "fart" added to their vernacular. Nice about that other area you drive through...wouldn't shock me if we ran into some of that as well. You just reminded me that I'm going to need to think about where we want to stop for gas since stops in the middle of the night aren't quite the same as day stops.
). We've had to write them off ever since DD6 was diagnosed with nut allergies. 
the drive there is always a bit more fun than the drive back, lol. But it's all good.
Ugh... that is so the truth! Our drive is about 20 hours. It was the worst for me when we were about 5-6 hours away from being home: you've been in the car for a long time already, you're not particularly close to being done, and your only reward at the end is going back to the real world? That's rough.
the drive there is always a bit more fun than the drive back, lol. But it's all good.
My poor mother was so disappointed when we learned the words "pee" and "fart". She preferred "passed gas", too. Pee, especially, though, she never got over and said it was the place we were raised. Everyone said it. She swore that nobody said that in Chicago. Until the day she died, I'd say I had to pee and she'd say "go to the bathroom" or "Oh, Luv!!" In a disapproving way. Smartass that I am, I'd say, "Oh, sorry, I forgot that people in Chicago don't pee. I shall goeth to emptieth my bladder."
Now that she's dead, I think I should have taken it easier on her, lol. Even into my thirties, I still teased her. But life is no fun if you don't tease your mother.
I hope you have a great trip and a great road trip, too! Do a TR and let us know how it went. If you have an iPad or something, you could kill some time doing an LTR from the car!
I might just have to use that if I get any questions about leaving my meeting tomorrow a bit early. 
Although, this does bring up another area for discussion while on the road...finding nicer ways for DH to tune out my mom over Thanksgiving. She's just a "little" chatty. Who knows, maybe we can even plan our escape in case I lose my temper w/SIL's mother. That's a whole different can of worms, but that's sure to keep me awake on the drive! , but I can't see us doing an LTR. I take a TON of pictures, so I tend wait on all of my Flickr uploads to do my report + it's sort of therapy for me getting over the post trip sadness. Although, we could probably talk about pictures we want to make sure we take on the way there and i could probably start editing pics on my laptop on the way back.