sockdolager n.

1830, with many spelling variants, "a decisive blow" (also, figuratively "a conclusive argument"), American English, a fanciful formation from sock (v.1) "hit hard," perhaps via a comical mangling of doxology, on a notion of "finality." The meaning "something exceptional" is attested from 1838.

Sockdologizing likely was one of the last words President Abraham Lincoln heard. During the performance of Tom Taylor's "Our American Cousin," assassin John Wilkes Booth (who knew the play well) waited for the laugh-line:

Don't know the manners of good society, eh? Well, I guess I know enough to turn you inside out, old gal—you sockdologizing old man-trap.

Amid the noise as the audience responded, Booth fired the fatal shot.