Late night conversation last night in wider company produced the question: “Where does the word shindig, come from?” The questioner thought that it might have Irish origins. Not quite but mayhap. The origin is Scottish. Online Etymology Dictionary dates it to 1871 (dance, party, lively gathering) and adds that it probably came from the word shindy (1821) which meant “a spree, merrymaking.” Reaching further back, we get shinty, which was a kind of hockey-like game called, even earlier (1670s), a shinny. And that word, discounted by the word “perhaps,” comes from Gaelic sinteag, meaning a bound or a leap. The same word, but used as a verb, as in to shinny, meant to climb a rope, presumably using the shins and the ankles. So shins are—remotely—involved. And, for good measures, you might have jumped up on the rope a little executing a sinteag.
Our Dictionary of American Slang, using the word “probably” (useful, these words, for etymologists) dares to be literal and says “a blow on the shin incurred while dancing,” saying they found this usage in 1859, adding “perhaps [!] by folk etymology fr the older shindy.” That dictionary also associates the word with a clambake.
Next time you’re invited to a shindig, leap to the occasion—and wear a tartan skirt or, if you insist on honoring the Irish, green.
Wikipedia has an article on Shinty here as it is still played in Scotland. Twelve players on each side. The image from the old days comes from a history of field hockey here. In Wales the game was called Bandy—now only played on ice. Ice… Ah! It has such a nice sound on this last day of a hot July!