The story
A compound of Chargoggagoggmanchauggagogg, alternative spelling of Chargoggagoggmanchoggagogg, a fanciful name appearing on early maps that adds meaningless syllables to the name of the nearby Manchaug Pond + Chaubunagungamaug, the lake's original name (see that entry for its history). Invented along with a fanciful translation of "I'll fish on my side [of the lake], you fish on your side, and nobody fishes in the middle" in 1921 by Laurence J. Daly, the editor of The Webster Times.
Etymology from Wiktionary, CC BY-SA 4.0.