I pinky swear!... But what?

To pinky nose, or make a pinky promise or Piggy promise, is when two people entwine their pinky fingers to signify that a promise has been made. It is often seen in anime, where it is called a yubikiri.

It is also possible for a pinky swear to exist between 3 parties, known as a 3-way pinky promise. A pinky swear between 4 or more people is relatively unknown.

Traditionally, the pinky swear is considered binding and tantamount to a handshake for sealing a deal. 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 signifies a promise that cannot be broken or counteracted by the crossing of fingers or other such trickery.

The Pinky Swear can be broken if a third party does not know of the promise. Pinky swears are also only valid if all parties agree prior to interlocking pinkies. A pinky swear is also often referred to as the Piggy promise; it comes from using your piggy finger known from the song This Little Piggy and is considered as being more important than the traditional pinky promise. If a pinky promise is broken, all other pinky promises with that person are cancelled and that person may no longer use pinky promises unless they can make it up to the person they pinky promised.

A pinky swear/promise is not allowed to be broken if each member has taken the promise/swear under his own free will. A variation to "strengthen" a pinky swear is to stamp or press your thumbs together after intertwining pinkies and stating the promise. It seals the deal.

The pinky swear is also made stronger if the bond of friendship is strong. If the swear is broken, it is safe to say that they are not a true friend and you should no longer consider them to be one, or should you?

source: Wiki