[The Squatter of Amon Rûdh]

Going from the description in the book, I'd say it went something like this:

Sauron is gazing into his Palantír. By his side is a small table bearing a mug of ale and a bowl of assorted dainties. He is watching the big match

Sauron: Foolish mortals! They cannot stand against the might of Sauron! My army will crush them like ants, and when the treasure they bear is in my hands I shall rule this world as I see fit. I shall punish this interfering lackey of the Valar with torments he has not imagined in his most terrifying nightmares! You surprise me, Olórin: I knew you to be a fool, but I did not believe that you would prove a madman! You will be cast into my deepest dungeon to be a plaything of my captains, but first you will watch as I break your petty king in pieces before you.

At this moment at the Sammath Naur Frodo claims the Ring

Sauron: What? One dares to challenge me here in my own realm? Fly, my Nazgûl! Bring him before me, and the Ring to my hand. Your failure is at hand, Olórin. It was a bold stroke but you should have known that it would fail, for none may cast aside the One. You have proved the weaker, as has your puny emissary.

He turns back to his Palantír, just in time to see an Orc cut down a man of Gondor with a particularly vicious back-hander

Sauron: Oh, well played, that man! Bravo! Bring me that pretend King, my minions! Bring him to me alive! Wait a moment: where's that idiot pretender gone? He's not wearing it. What's he done with my precious Ring? No! He cannot have done it! I myself could not do it! Stop him, ye wraithlords! Your own existence hangs in the balance! Stop... Oh, sod it.

As the Ring falls into the boiling heart of Mount Doom, Sauron waves his fist at the ceiling

Sauron: If this is your idea of a joke it's in poor taste even for you, you ba...

Sauron boils away into a shadow of malice. Barad Dûr collapses; the army of Mordor crumbles; eucatastrophe reigns, etc, etc.