Meaning

noun a burrowing ground squirrel of western America and Asia; has cheek pouches and a light and dark stripe running down the body

origin1832; alteration (influenced by chipping squirrel) of earlier chitmunk, from older Ojibwe ačitamo˙nˀ (“squirrels”) (modern ajidamoo), literally ‘those who descend headlong’, from ačit- (“headfirst, face-down”) (compare modern ajijibizo (“he falls headfirst”), ajidagoojin (“he hangs upside down”)). The English verb developed due to the high-pitched voices of the American puppet and cartoon…

Etymology from Wiktionary, CC BY-SA 3.0