What are the most toxic rivalries in college football?

On the Wikipedia rivalries thread, someone mentioned Penn State and Pitt as a Top 5 most toxic rivalry in college football even if it's no longer annual, which I would agree with, it takes a quick search in this sub to prove that point of the animosity between our fanbases. What are the other most toxic rivalries in college football?

The 2 that come to mind besides Pitt-PSU for me are A&M-UT and Michigan-Michigan State. All 3 of these sets have a lot of bad blood between them and each have a school that considers itself the academic and athletic big brother within their state. There's also conference entrance sabotage between all these schools.

I guess Utah-BYU is another one which has a lot of vitriol. Which rivalries am I missing?