TLDR right away! What was, in your opinion, the biggest "FUCK YOU" to the audience that you ever witnessed in a movie, tv show, book, video game, anime, manga etc.
Okay then, let's talk about last episode of Game of Thrones!
I am seething with rage and infuriation. And don't get me wrong, I'm not against good characters getting killed. I think that the Red Wedding was brilliantly done and felt not forced and even somewhat natural in the flow of events as a whole. But the conclusion of that fucking fight between Viper and The Mountain just really felt like a giant "FUCK YOU" to the whole audience! Here we have an amazing new character with interesting backstory portrayed by a very good actor. And now he's gonna get brutally murdered by a FUCKING CARICATURE whose actor was replaced two times! And don't even get me started on how freaking bullshit that death was! You telling me that someone with skills and reflexes of Oberyn wouldn't be able to just roll away quickly after getting knocked down? Or that he wouldn't be able to block one hit to the face? And that even Mountain would be able to do all that after getting hamstrung, pierced through the chest AND poisoned?! It all just felt forced! Like Martin was thinking "There's no way I can just let more skillful warrior win! Let me check up my ass... oh, here it is!"
Sigh... anyway, what about you people?
I too had the same fuck you moment, but for different reasons.
They pulled off Oberyn well, but they made the fight swing too hard in his favour. Whilst I admit that it's gonna be hard to recreate the 8 foot monstrosity that is the Mountain in the books, who managed to fight toe to toe with Oberyn despite the fact that he was sporting a war wound and had already been poisoned once in the fight; the Mountain in the show felt severely diluted. Having that severely diluted strongman killing Oberyn felt cheap, because Oberyn had outclassed him until that point. The Cleganes are supposed to be borderline inhuman.