What is the origin of the phrase "pinky promise"?

Question

A pinky promise (or "pinky swear") is a gesture in which two parties interlock little fingers in a symbolic gesture of agreement. What is the origin of this phrase?

One possibility, and probably the most straightforward one, is that it is an independent invention to describe an existing cultural practice of sealing promises by interlocking little fingers.

Another possibility, however, is that it originates from Japanese. Japanese sources frequently suggest that the English phrase "pinky promise" is a translation/adaptation of a similar Japanese concept called 指切り (yubikiri, lit. "finger-cutting") which supposedly has its origins in yakuza loyalty practices (if someone promised to do something and performed a yubikiri, and then broke their promise, their finger would be cut off).

However, as Wikipedia notes, this practice (if not the exact phrase "pinky promise") has been attested since 1860, as recorded in Bartlett's Dictionary of Americanisms. The Japanese yubikiri predates that¹, so it's still possible that "pinky promise" derives from yubikiri, but I can't imagine there were many borrowings/translations from Japanese that long ago.

¹ The Nihon Kokugo Daijiten, which is closest thing Japanese has to the OED, attests yubikiri in the sense of "a promise" from 1638, and in the sense of "cutting off a finger" from 1692.

Answer 1

There's a Japanese and Chinese tradition called "red thread". Wedded couples tie a red thread on their pinky finger, because they believe that it was destiny that connects them together. The red thread signifies eternal togetherness. You use your pinky finger as a promise that you are never supposed to break.

From that tradition a popular kid's rhyme:

指切りげんまん

うそ付いたら

針千本飲ます

指切った

Which means:

Cut your finger and swear

Should you lie

Swallow a thousand needles

Cut your finger

So we see there is long standing traditions that were used in Japan to denote a truly high promise to the pinky. Then it became popular for the Japanese mafia used to cut off a finger if you did something they didn't like or lied them. Usually pinkies were the first to go. You can see this in some Japanese cartoons too.

This was brought to US from immigrants and movies. I am not sure where/when it became a "cute" thing to do. Because two people who did not know each other well would not pinky swear. Definitely alteration after acceptance.

Answer 2

I can't offer any academic research, but my experience as a father is that this is the "little-girl" equivalent of a hand-shake. My daughter (now 21, but still my little girl of course) and her friends or her mom often make this gesture. I have always assumed that it was named from the action of interlocking pinkies rather than shaking hands. Seems much more likely than the alternative mentioned here.

Answer 3

Google Books search results for pinky promise, pinkie promise, pinky swear, and pinkie swear indicate that "pinkie swear" is the earliest of these four variants. Easily the earliest instance of any of the forms is from Don Appell, A Girl Could Get Lucky (1963), although it refers to a different gesture than the one familiar today, which involves two people interlocking their little fingers:

PENNY. I sure do. See that coffee table? I made it.

ANDY. Come on!

PENNY. Pinkie swear! (She kisses her pinky and lifts it skyward.) I mean, I didn't make the marble top. I had to buy that.

...

ANDY. Come on. You're making it up.

PENNY. No, I'm not! Pinkie swear! That's not the worst of it.

The next Google Books mention of "pinkie swear" is in Companies and Their Brands (1990), which notes the existence of a New York company called Pinkie Swears LLC. Six other instances appear between 1994 and 1997.

Pinky swear first appears in the Library of Congress's Catalog of Copyright Entries for July–December 1973, in a song titled "Pinky swear, I love you." Other early instances appear in 1983 and 1984.

The earliest Google Books instance of pinkie promise is from Betty Dorion, Melanie Bluelake's Dream (1995):

Melanie stood still. "Pinkie promise," she said, holding up her little finger. "We'll write each other every week."

Rachel curled her little finger around Melanie's. "Pinkie promise."

Instances of "pinkie promise" follow in 1998, 1998, 1999, and 1999, and 2000.

For the variant pinky promise, the earliest match is from 2000 in The Palimpsest Review.

The upshot of these results is that Google Books searches find many matches for one or another of the variants from about 1990 onward, but no relevant matches from before 1963. That 1963 match is interesting to me in several ways, including the unusual gesture made in expressing it, and the fact that it dates back to my childhood. I never heard pinkie promise (or pinkie swear) used until, I believe, the first Monsters Inc. movie (2001), which suggests that the term may have been regional, not national, in the United States during the earliest decades of its use.

Answer 4

The word pinky comes from Dutch (Pinck) through Scots into English meaning something tiny. Pink eye meant the small slit left to see through, rather than the color of the eye (which, of course turns red). Pink is a small pink colored flower, from where we then get the name of the color pink. Pinking shears, for example, are small scissors. Young people are subject to the whims of their parents and so are sometimes incapable of fulfilling their oaths or don't understand the gravity of an oath. The Bible warns of making false oaths or leaving oaths unfulfilled as sinful. Therefore, children have long been forbidden to make oaths(eg. we still don't let them sign contracts). So, a "pinky swear" is a "small oath" or perhaps an oath by a small one -- up to the limits of what they can pledge. The addition of touching pinkie fingers is a natural follow-on from there, since both are "pinkies," and a little version of shaking hands on a promise as done by adults.