gachiGASM and gachiBASS refer to BetterTTV Twitch emotes featuring an image of Gachimuchi muscle man Billy Herrington, which is often used as a reaction to indicate intense pleasure or satisfaction in a similar vein to the Kreygasm emote.
According to a comment submitted to /r/forsen by Redditor sc2pal on December 3rd, 2015, the gachiGASM meme started after a Billy Herrington wrestling remix was played on the social music streaming site plug.dj, which was subsequently adopted by Twitch streamer Sebastian “Forsen” Fors.
On October 13th, 2015, the GamesPlace YouTuber channel uploaded footage of Forsen playing Hearthstone titled “Forsen – gachiGASM,” in which viewers spam the word “gachiGASM” in the chat window (shown below, left). On October 7th, 2016, Redditor GreySM submitted a post asking “How to make gachiGASM a global BTTV emote?” to /r/forsen. On October 20th, YouTuber Camouflaged submitted several songs in a playlist titled “GachiBASS Radio,” featuring an animated image of the Billy Herrington emote (shown below, right).
On October 26th, 2016, Redditor LazyDoggie1337 submitted a post titled “gachiBASS removed from bttv” to /r/forsen. On May 15th, gachiGASM was added to the FrankFaceZ Twitch chat extension (shown below).
On April 9th, 2017, YouTuber TOP KEK uploaded a mashup song titled “Fast gachi – mashup gachiBASS Clap” (shown below).