What a tough year to answer this question! I became a Canes fan in the mid-80s, so I have a special hatred in my heart for ND and mouth-full-of-marbles idiot Lou Holtz. But in terms of disaster, losing to a ****** FSU team coming off a two-win season with a midget for a QB would be absolutely embarrassing. So, long answer short:
FSU
Followed by: UF (I'm putting UF above ND because ND actually has a decent team while the Gator is just shiit.)
Followed by: ND