Green’s Dictionary of Slang

(US) a dolt, a simpleton, a fool.

1979		J. Charyn Seventh Babe 39: He was contemptuous of all the chuggerheads he had to meet day after day, country boys who had trouble with their own signatures [HDAS].
1979		D. Gram Foxes (1980) 86: They showed no inclination to slow down. He came within a breath of getting steamrollered by two of the lumbering chuggers.