I guess we're done voting but I'd have gone with Bo's first loss to UCLA because I remember thinking we had a coach entering his 5th year at the time going up against that Mora in his first season and they were clearly more disciplined, organized, etc. That was the writing on the wall game for me, in other words, as far as Bo was concerned.
As far as the worst loss in terms of embarassment, though, I just think there were too many for one to really stand out. Iowa State probably makes the most sense.
Part of me thinks the win against McNeese State was really a loss. If not for Ameer's heroics, we're as big a joke as Michigan. How many batteries does it take to beat scUM? I suppose that maybe that didn't work by then if we were going with FCS instead of AA but you get the point...