Loki breaking his back a billion times in Avengers.
Bonus:
Loki getting the ass-whopin’ of his life by The Hulk was prolly the second best part of The Avengers. The absolutely best part is when Captain America tells The Hulk to Smash, that shitty grin he has on his face tells a lot more then one would think, for me, it told me that The Hulk is not some mindless beast who only knows destruction, but it was a flash of intelligence and understanding. The third best part, which is not shown in this sequence is when The Hulk deadarm punches Iron Man after the fight is over.