GSP vs Serra - This one was pretty humiliating for GSP in the sense that it was one of the biggest (maybe the biggest?) upsets in UFC history.
Couture vs Ortiz - That's a great one! I would have to rewatch because I barely remember how the rest of the fight went. I remember Randy took the easy UD. The most humiliating parts was Randy spanking Tito... to punish him for talking shit.
Ronda/Holm and Rose/JJ - love both of these since Ronda and JJ were both such cocky, smack talkers that were so very humbled.
Another honorable mention would be Valesquez vs JDS 1 - JDS spoiled the party (first UFC show on Fox??) by knocking him out too quickly for UFC's taste, I think.