Michigan State.
I never, ever want to lose to Michigan, so that's not an option. I'm old enough to remember USC breaking our hearts in the 1975 and 1980 Rose Bowls (both by a single point, and the 1980 loss costing us the 1979 NC). I want to beat those fuckers in the worst way, so they're "non-option #2". As much as I'd be excited for my hometown team YSU to score a monumental upset over a I-A all-time powerhouse, I don't want it to be at our expense. I hate Wisconsin, so there's another non-option. We've never lost at home to Penn State since they joined the conference, and I want JoeGrandpa to go out 0-fer in The Shoe...another non-option. Can't afford to lose to Ohio or Troy, so they're out. I don't ever want to lose to Northwestern again...they're out. I don't want to let Illinois think they can start another 5-game win streak as they did in the early '90s, so they're out. Out of the remaining games. losing at MSU to Mark Dantonio would be the most tolerable by far.
If we lose only one game and it's at Michigan State, with us winning a BCS bowl game, I will be quite happy.