The story
From chunk. Compare humongous (“extremely large”, adjective) or dingus (“any object or thing; a foolish person”, noun), and chonk. James Stephanie Sterling was credited with coining the term “chungus” in 2012, though it did not see wide usage until around 2018 with the rise of the “Big Chungus” meme. The Big Chungus meme is derived from the Looney Tunes episode Wabbit Twouble.
Etymology from Wiktionary, CC BY-SA 4.0.