Great thread.
Nastiest weather I've ever experienced attending a game at Memorial Stadium was our 17-12 win over #5 Colorado. We were #4 at the time, and that win propelled us to #3. Unfortunately it was this nasty weather game that I'm convinced gave half our team the flu, which killed us (and our very likely trip to the national title) the following week in the Big 12 championship vs Texas.
I don't want to stray into that awful topic, so I'll finish by saying that after the game I threw my cold, soppy clothes in the dryer, pulled them out and put them back on, and (God is my witness) those hot clothes never felt so good