The one true most tragic scene from George R.R. Martin's A Storm of Swords

Prince Oberyn is speaking to the dwarf Tyrion:

"Elia found it all exciting.  She was of that age, and her delicate health had never permitted her much travel.  I preferred to amuse myself by mocking my sister's suitors.  There was Little Lord Lazyeye, Squire Squishlips, one I named the Whale That Walks, that sort of thing.  The only one who was even halfway presentable was young Baelor Hightower.  A pretty lad, and my sister was half in love with him until he had the misfortune to fart once in our presence.  I promptly named him Baelor Breakwind, and after that Elia couldn't look at him without laughing.  I was a monstrous young fellow, someone should have sliced out my vile tongue."

Yes, Tyrion agreed silently.  Baelor Hightower was no longer young, but he remained Lord Leyton's heir; wealthy, handsome, and a knight of splendid repute.  Baelor Brightsmile, they called him now.  Had Elia wed him in place of Rhaegar Targaryen, she might be in Oldtown with her children growing tall around her.  He wondered how many lives had been snuffed out by that fart. (p. 795)

A true tragedy indeed...