In the United States, the pinky swear has existed since at least 1860, when Dictionary of Americanisms listed the following accompanying promise:
- Pinky, pinky bow-bell,
- Whoever tells a lie
- Will sink down to the bad place [sic]
- And never rise up again.
Pinky swearing presumably started in Japan, where it is called yubikiri (指切り, "finger cut-off") and often additionally confirmed with the vow "Finger cut-off, ten thousand fist-punchings, whoever lies has to swallow thousand needles." (指切拳万、嘘ついたら針千本呑ます "Yubikiri genman, uso tsuitara hari senbon nomasu"). The gesture may be connected to the Japanese belief that soulmates are connected by a red string of fate attached to each of their pinkies.
Recently in South Korea, the hooked pinky has been followed by a “seal,” wherein the thumbs touch each other while the pinkies are still hooked.
In modern times, pinky swearing is a more informal way of sealing a promise. It is most common among school-age children and close friends. The pinky swear signifies a promise that can never be broken.