The Brief: The term "GameStonk" is a reference to Game Stop stock and its surge in share price in late January 2021.

DEEP DIVE
A combination of the words Game Stop and stonk, the term “GameStonk” refers to the internet and meme-fueled rise in price of Game Stop stock in January 2021.
Gamestonk!! https://t.co/RZtkDzAewJ
— Elon Musk (@elonmusk) January 26, 2021