Entries related to jack-shit
As a portable contrivance for raising weight by force from below, 1703. As the name of a device for pulling off boots from 1670s. The jack in a pack of playing cards (1670s) is in German Bauer "peasant." Slang meaning "money" is by 1890 (in earlier slang it meant "a small coin"). Jack-towel, one sewn together at the ends round a roller, is from 1795. The jack of Union Jack is a nautical term for "small flag at the bow of a ship" (1630s) and perhaps is from the word's secondary sense of "smaller than normal size."
Old English scitte "purging, diarrhea," from source of shit (v.). Sense of "excrement" dates from 1580s (Old English had scytel, Middle English shitel for "dung, excrement;" the usual 14c. noun seems to have been turd). Use for "obnoxious person" is at least since 1508; meaning "misfortune, trouble" is attested from 1937. Shit-faced "drunk" is 1960s student slang; shit list is from 1942.
Up shit creek "in trouble" is by 1868 in a South Carolina context (compare the metaphoric salt river, of which it perhaps a coarse variant). To not give a shit "not care" is from 1922. Pessimistic expression same shit different day attested by 1989. Shitload (also shit-load) for "a great many" is by 1970. Shitticism is Robert Frost's word for scatological writing. Piece of shit "contemptible person" is by 1916.
The expression [the shit hits the fan] is related to, and may well derive from, an old joke. A man in a crowded bar needed to defecate but couldn't find a bathroom, so he went upstairs and used a hole in the floor. Returning, he found everyone had gone except the bartender, who was cowering behind the bar. When the man asked what had happened, the bartender replied, 'Where were you when the shit hit the fan?' [Hugh Rawson, "Wicked Words," 1989]