22/10/18 Pinky Swear

To pinky swear, or to make a pinky promise, is the entwining of the little fingers (“pinkies”) of two people to signify that a promise has been made.
In Japan, the pinky swear originally indicated that the person who breaks the promise must cut off their pinky finger. 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 means a promise that can never be broken.