He misspoke
"He misspoke" is a verbal game and meme originated by Destiny, MrMouton and Dan. The purpose of the game is to catch the other participants in a misspeak and bullying them about it. What was a funny game in the beginning became a major existential crisis for Dan who was the oldest of the participants. Because of his age Dan took the brunt of the bullying and was forced to take extended breaks from interacting with the stream.
The meme is now used within the DGG community when anyone misspeaks or mispronounces a word, with chatters typing "HE 
" when this occurs.