Trying to explain it is almost impossible. I usually say that OU is a big rival. We dislike each other. The week before and after that game are actually affected by what happens. That said, Sooner students aren't that much different than Longhorn students or Tech students or any students. It's just a game. Other than those two weeks, it stays in the back of the mind.
Aggies think we are genuinely evil and represent all that is bad in the world. They never cease obsessing on us and making embarrassing asses of themselves hissing when introduced to one. It happened to me in the workplace once. For us it's a game, for them it's a holy war around which they've invented myths and legends untethered from reality.
I think about them more often because I'm fascinated by fans who choose to be stalkers. You start to study their quirks and oddball notions then find yourself in a full anthropological analysis.
Of course, I exempt 2%ers who pretty much fit the same mold as students that we do. They want to beat Texas. They don't want to eat, drink, and think Texas all the livelong day.