What do YOU do when you and another person say something at the same time? Is saying "Jinx" and forbidding someone to talk a recent custom, or an ancient one?
As far as I can tell, the most common response to such a situation today is that one party will say "jinx!" The other will be forbidden to talk until someone says their name. While there are variations (when I lived in Georgia, the person would say "jinx! 1, 2, 3, you owe me a coke!," which is was recorded in the midwest in the 1970s as well), the "no talking" rule is probably more common (especially since it's been on both The Simpsons and Recess). This isn't exactly the kind of thing where there's a lot of data going around, though.
Saying "jinx" at all, though, is actually a fairly new custom, even though its roots might go WAY back. Calling "jinx" when multiple people say the same thing at the same time didn't really catch on in the U.S. until after World War 2. Prior to that, a more common response was that each party simply had to name a poet (almost invariably, according to most of the books on the right) the first kid would name Shakespeare, the second would name Longfellow). Some variations had kids locking pinkies first, and sometimes it was said to be an omen: if two people said something at once, one of them was going to get a letter.
However, the origins of the game MAY go back even further, back as far as the 16th or 17th century, when there was a popular Scottish tavern game called "High Jinks" (also known as "High Pranks" or "Whig-meleery"), in which one would shout "High Jinks!" before throwing dice. Whoever lost a round had to perform a penalty, usually impersonating some character or another. If they broke character for one second, they had to take a drink, put extra towards the tab, or some other such penalty. There are two things that suggest that the modern "Jinx" game could descend from this:
1. In some, two people rolling the same number at the same time led to extra penalties.
2. According to some modern scholars (the Knapps on the right), one of the characters people commonly had to play in forfeits was a mute - ie, one who couldn't talk.
I'm not totally sure as to the validity of the second part (I couldn't find any source saying that impersonating a mute was common, though it's not hard to imagine). More peculiar, really, is that by all accounts the game was mostly forgotten by the early 19th century. Still, the similarities to the modern game are hard to ignore! It's quite possible that, while it MOSTLY died out, a handful of people still played variations that filtered their way to the playground in the 20th century.
Some other variations on saying the same thing at the same time:
- Whoever finishes first will marry first, according to Cornish folkore (late 19th century)
- Each person should touch thumbs or pinkies and make a wish (all over America, throughout the early 20th century)
- In the UK in the 50s, some kids said that they cried "White rabbits," and that whoever said it first would get a letter.
- Also in the UK, the practice of saying the name of a poet would make a wish come true, but in some places you were banned from saying "Shakespeare" (because he spears the wish) or Burns (because he burns it)
- In Iowa in the early 20th century, kids would press thumbs together and say "philopena."
- In some parts of both England and the States, kids would run to the chimney, shout "Shakespeare" up it, and make a wish. Sometimes in the states, this was followed by them saying "What goes up the chimney?/ Smoke!/ I wish this wish / may never be broke."
It's interesting that almost all of these were to do with getting good luck or wishes. But sometime after world war 2, it became (or re-became) a bit darker!