Will add gifs and memes to this page as I find them. Warning: SPOILERS BELOW.

Reddit comments:

http://reddit.com/r/gameofthrones/comments/271bb5/season_4_tonight_is_the_night/

http://reddit.com/r/gameofthrones/comments/26x86s/season_4_spoilersspeculation_predictions/

Reddit discussion of this episode:

http://reddit.com/r/gameofthrones/comments/272m7f/season_4_spoilers_premiere_discussion_408_the/

Sansa Stark transformation gif:

http://pandawhale.com/post/44846/sansa-stark-shall-we-go-gif

Grantland recap:

http://grantland.com/hollywood-prospectus/game-of-thrones-recap-the-rumble-in-the-red-keep/

Pedro Pascal (Oberyn Martell) practicing:

http://pandawhale.com/post/44860/pedro-pascal-oberyn-martell-practicing-for-the-fight

Arya Stark laughing:

http://pandawhale.com/post/44867/arya-stark-laughing-gif

Tyrion Lannister reacting:

http://pandawhale.com/post/44871/the-mountain-and-the-viper-tyrion-reaction-gif

Oberyn and the Mountain off camera:

http://pandawhale.com/post/44874/oberyn-and-the-mountain-off-camera

More High Quality gifs from The Mountain and The Viper:

http://pandawhale.com/post/44934/the-mountain-and-the-viper-high-quality-gifs-game-of-thrones-s4e8

Mountain vs Viper win probability chart:

http://pandawhale.com/post/44944/the-mountain-vs-the-viper-win-probability-chart

Mountain vs Red Viper comic:

http://pandawhale.com/post/44933/red-viper-vs-the-mountain-combat-comic-by-jeff-mccomsey

If Tyrion dies, we riot.

http://pandawhale.com/post/45067/if-tyrion-dies-we-riot

Oberyn Kenobi:

http://pandawhale.com/post/45068/if-you-strike-me-down-i-shall-become-more-powerful-than-you-can-possibly-imagine-oberyn-kenobi

The Mountain and The Viper happy ending:

http://pandawhale.com/post/44989/the-mountain-and-the-viper-happy-ending-with-8-ways-to-make-game-of-thrones-s4e8-ending-better-aka-oberyn-vs-mountain-the-denial-version

Say her name! Elia Martell! You raped her! You murdered her! You killed her children!!

Who gave you the order???

And all the Oberyn and Tyrion fans go...

Spoiler comic:

http://mccomseycomix.wordpress.com/2013/06/26/the-red-viper-vs-the-mountain-that-rides-a-12-page-comic/

Reddit comments about the final scene:

http://reddit.com/r/gameofthrones/comments/272r62/s4e8_that_ending_though/

http://reddit.com/r/gameofthrones/comments/272ruh/s4e8_thank_you_book_readers/

http://reddit.com/r/gameofthrones/comments/272rzf/s4e08_remember_what_bronn_said_to_tyrion/

On Pedro Pascal's Twitter tonight:

Reddit comment:

I hate that they left out the part were Tyrion says, " I'm feeling more innocent by the minute " when The Red Viper was winning. That adds a lot dramatically.

More:

http://reddit.com/r/gameofthrones/comments/272vgl/spoilers_e8s4_in_the_category_of_things_put_mildly/

I have an idea.  Oberyn can live on as a hologram and randomly appear on other programs.

I'm not ready to let him go.

I like that idea. I'm not ready to let go either!

So apparently Pedro Pascal has a thing for Captain Crunch.

Someone asked how I feel about Captain Crunch: I'm capable of eating an entire box of it without any milk. It is a sweet taste that is indescribable, Captain Crunch is its own flavor.

Dat foreshadowing in his Reddit AMA:

http://reddit.com/r/IAmA/comments/26gtvt/i_am_actor_pedro_pascal_i_play_oberyn_in_game_of/chqxoae

Too soon, too soon!

Then I guess I won't be needing this anymore.

Reddit comments:

http://reddit.com/r/gameofthrones/comments/272g55/all_show_all_set_for_game_night_get_hype/

Too soon?

Too soon?

Dammit, GRRM, you're not gonna make this easy for us, are you?

Reddit comments:

http://reddit.com/r/gameofthrones/comments/272zbr/s4e8_oh_cersei/

Oberyn: "I always drink before a fight."

Tyrion: "It could get you killed. It could get me killed."

Oberyn: "Today is not the day I die."

Ellaria: "You're going to fight that?"

Oberyn: "I'm going to kill that."

Ellaria: "He is the biggest man I've ever seen."

Oberyn: "Size does not matter when you are flat on your back."

Tyrion: "Thank the gods."

Too soon?

Lord Varys and Oberyn Martell in Game of Thrones season 4 episode 6:

Dat foreshadowing.

Interesting theory: "Oberyn was trying to push Dorne into the war. He could've killed Clegane, and that would've been it. If he heard the confession that the Lannisters were involved, he's got reason to convince his older brother to go to war."

Source:

http://reddit.com/r/gameofthrones/comments/272vgl/spoilers_e8s4_in_the_category_of_things_put_mildly/chx2jhb?context=3

And: "That was what he wanted all along. He could easily assasinate the Mountain but what he wanted is his confession. He also wanted to prove for sure that Tywin was behind this, he didn't get that much but it is interesting that this was in public, so now everyone knows for certain that it was Lannister's main man that killed Elia. I'd love to see the consequences of that for Tywin... the war is barely over and already new conflict is brewing in the North, Stannis is having his second wind, last thing Tywin needs is Dorne making a move, either political or military."

Source:

http://reddit.com/r/gameofthrones/comments/272vgl/spoilers_e8s4_in_the_category_of_things_put_mildly/chx1f0i?context=3

Never leave me alone in this world.

http://pandawhale.com/post/44893/never-leave-me-alone-in-this-world-ellaria-sand-to-oberyn-martell-s4e8

That look between Jaime and Varys...

Imgur comments: http://imgur.com/gallery/XPg18

Reddit comments:

http://reddit.com/r/asoiaf/comments/274wil/spoilers_all_the_glance_between_jaime_and_varys/

Here's a really good analysis of the Beetles scene and the Trial by Combat scene:

http://pandawhale.com/post/44948/the-mountain-and-the-viper-analysis-the-beetles-scene-and-the-fight-scene-line-up-almost-perfectly

Mind blown!

Could you please use another expression?   

Oh. Right. Sorry. Too soon.

Those Oberyn moves!

And... Scene!

Reddit comments:

http://reddit.com/r/gameofthrones/comments/272uua/season_4_the_red_viper_vs_the_mountain_clip/

This was a great shot:

And how about that Arya Stark laugh?

The best!

Reddit comments:

http://reddit.com/r/gameofthrones/comments/273029/s04e08_aryas_laugh/

The 100M version: http://gfycat.com/PossibleShadowyGelding

High quality Arya laughing gifs: http://pandawhale.com/post/44867/arya-stark-laughing-gif

Tyrion wanted to know all the words for kill? http://phrontistery.info/kill.html

Fratricide is brothers. Filicide is sons. Nepoticide, that's the one. Matricide, Patricide, Infanticide. Suicide. There's no kind of killing that doesn't have its own word.

Cousins.

Cousins... you're right. There is no word for cousin killing. Well done.

Anyone remember Jamie killing his cousin Alton Lannister, back in season 2?

It was a nice touch to allude to that.

Reddit comments:

http://reddit.com/r/gameofthrones/comments/272ynn/s4e8_theres_no_kind_of_killing_that_doesnt_have/

Sansa dropped by The Vale's Hot Topic:

Reddit comments:

http://reddit.com/r/gameofthrones/comments/272v2i/s04e08looks_like_sansa_dropped_by_the_vales_hot/

Higher quality version of this gif:

http://pandawhale.com/post/44846/sansa-stark-shall-we-go-gif

How DO 102 men stop 100,000?

Grey Worm sees Missandei and he likes!

The pillar and the stones!

So we have to call that guy Ramsay Bolton now? Man do I hate that guy.

"Traditions are important. Where are we without our history?"

The Vale dude says, "You have foreign blood, don't you Baelish?"

Littlefinger had a great grandfather from Braavos!

Sansa had met Lord Royce in S1E1:

http://pandawhale.com/post/44862/sansa-stark-met-the-vales-lord-bronze-yohn-royces-son-ser-waymar-in-s1e1-lord-royce-is-father-of-the-very-first-casualty-in-the-series

On Sansa's transition:

http://pandawhale.com/post/44855/game-of-thrones-showrunners-and-george-rr-martin-talk-the-evolution-of-sansa-stark-comicbookcom

Did... Did Jorah just get kicked out of the friend zone?

Ser Barristan: "You'll never be alone with her again."

Ser Jorah: "I have loved you."

Daenerys: "Love? How can you say that to me? Any other man, and I would have you executed. But you, I do not want you in my city, dead or alive. Go back to your masters in King's Landing and collect your pardon, if you can... Don't ever presume to touch me again or speak my name."

Harsh!!!

Did... Did Ygritte just show compassion to Gilly?

Reddit comments:

http://reddit.com/r/gameofthrones/comments/2731jw/s4e8_ygritte_showing_a_small_spark_of_humanity/

What if Ygritte is preggers?!

Entirely possible Ygritte is pregnant. That would be an interesting development!

"Wine always helps." ~Tyrion to Jaime

Oh the irony! He even tried to get Oberyn to wear a helmet!

Is GRRM the cousin killing beetles?

Refer to the penultimate scene between Tyrion and Jamie. They talk of their simple cousin who spent his days smashing beetles. Tyrion is fascinated by his moronic actions while family legacies and Targaryen dragons fade into the background. All that's left is the sound of the killings. "And I still couldn't figure out why he was doing it, and I had to know because it was horrible that all these beetles should be dying for no reason." Orson gave no answer and he kept on killing until he was kicked in the chest by a mule and died.

Reddit comments:

http://reddit.com/r/gameofthrones/comments/272wmi/all_show_george_r_r_martin_is_the_cousin_killing/

http://reddit.com/r/gameofthrones/comments/272tgy/s04e08_spoilers_the_beetle_speech/

Reddit comments:

http://reddit.com/r/gameofthrones/comments/272utu/s4e8_someone_requested_this_as_a_gif/

Stealing this from the /r/asioaf thread (spoilers all), which sounds like a good explanation:

Tyrion is asking his brother why his sister and father keep wanting to smash him for no good reason. And Jaime is sad because he doesn't know either. Tyrion is afraid he will die never knowing why, just as their cousin never knew why he smashed beetles.

All beetles must die.

Higher quality gif: http://gfycat.com/PleasantWeeCoypu

Dammit, Cersei.

Reddit comments:

http://reddit.com/r/gameofthrones/comments/272zbr/s4e8_oh_cersei/

Tyrion reaction gif: http://pandawhale.com/post/44871/the-mountain-and-the-viper-tyrion-reaction-gif

All beetles must die.

http://pandawhale.com/post/44889/guns-dont-kill-people-george-rr-martin-kills-people-grrm-also-kills-beetles

Jaime Lannister redemption arc:

Reddit comments:

http://reddit.com/r/gameofthrones/comments/27787h/spoilers_s04e08_something_i_noticed_in_the_last/

Preview of episode 4.09:

Reddit comments:

http://reddit.com/r/gameofthrones/comments/272shi/season_4_episode_9_preview_the_watchers_on_the/

Summary and analysis of "The Mountain and The Viper" for non book readers:

http://pandawhale.com/post/45099/game-of-thrones-s4e8-book-speculation-followup-for-non-readers-the-mountain-and-the-viper