In his essay entitled "In the Shadow of the Rock: Thomas L. Crittenden, Alexander M. McCook, and the 1863 Campaigns for Middle and East Tennessee," which appears in The Chickamauga Campaign (Steven Woodworth, ed.), Ethan S. Rafuse quotes a contemporary describing Gen. Alexander McDowell McCook as a “chuckle head:”
By March 1863, however, Perryville and Stones River had done enough damage to McCook's reputation that relatively few in the Army of the Cumberland were still expressing such confidence [in him]. Indeed, that month one officer expressed what was undoubtedly a more widely held sentiment when he proclaimed the “young and very fleshy” McCook “a chuckle head.” McCook, he added, was a man who “swear[s] like a pirate and affect[s] the rough-and-ready style,” which combined with his grin to excite “the suspicion that he is either still very green or deficient in the upper story.”
All of which got me wondering about the origins of the term “chucklehead.”
Until I saw the quote, I would have imagined the term was of fairly recently vintage. Doesn't it sound like some sort of 1950s thing? “You chucklehead, you!” As it turns out, nope.
Extensive research (consisting of a few clicks on Google) suggests the term goes back to the Eighteenth Century and “is perhaps connected with” the verb “chuck,” "'to throw,' 1590s, variant of chock 'give a blow under the chin' (1580s), possibly from Fr. choquer 'to shock, strike against.'"