O.E. socc "light slipper," a W.Gmc. borrowing from L. soccus "light low-heeled shoe," variant of Gk. sykchos "a kind of shoe," perhaps from Phrygian or another Asiatic language. The verb meaning "to stash (money) away as savings" is attested from 1942, Amer.Eng., from the notion of hiding one's money in a sock. To knock the socks off (someone) "beat thoroughly" is recorded from 1845, Amer.Eng. colloquial. Teen slang sock hop is c.1950, from notion of dancing without shoes.
1700, "to beat, hit," of uncertain origin. To sock it to (someone) first recorded 1877.