He's just smashing the beetles, folks.

Reddit comments:

http://reddit.com/r/gameofthrones/comments/275jq8/spoilers_all_how_i_imagine_george_rr_martin_right/

Guns don't kill beetles. GRRM does.

All beetles must die.

GRRM, what is best in life?

Imgur comments: http://imgur.com/dlK47Bf

Reddit comments:

http://reddit.com/r/gameofthrones/comments/2755uh/no_spoilers_guns_dont_kill_people/

Btw lol at the Imgur comments. 

Game of Thrones - The Mountain and The Viper has the story of the beetles:

http://pandawhale.com/post/44839/game-of-thrones-season-4-episode-8-the-mountain-and-the-viper-gifs-and-memes

Kung!

Reddit comments:

http://reddit.com/r/gameofthrones/comments/27c4wc/s4e08_kung/

Someone in /r/asoiaf pointed out that the scene is a jab at Orson Scott Card, who wrote a negative review of the showing after watching the first 2 episodes, because he doesn't like boobies.

Orson Lannister, a dimwit, smashes beetles/buggers over and over, leaving the observer to wonder, as Tyrion did, what's going on in his mind. Is there a point? Or is Orson just a stupid simpleton?

The post in question:

http://reddit.com/r/asoiaf/comments/277wqd/spoilers_s04e08asos_my_analysis_of_the_orson/chyac72

The beetle smashing is noted to be a mockery of the premise of Ender's Game.

The GRRM reaper!

Reddit comments:

http://reddit.com/r/gameofthrones/comments/27bu06/s4e8_i_think_i_know_who_he_really_is/

Here's a 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

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