BYU, Oregon State, Oregon, Boise State.
I know it's four, so sue me.
Any smaller team playing an SEC or Big 10 team (I love watching Florida and Ohio State get beat).
Growing up in the late 70s and early 80s, I loved Oklahoma and USC. Oregon State and Oregon pretty much sucked back then. I watched the occasional BYU game with my Dad, but didn't really become a die-hard fan until I went to school at BYU in 1986.