One Thousand Years of Death

is a very simple technique with an overly dramatic name, One Thousand Years of Death is little more than inserting one's index and middle fingers (similar to the Tiger hand seal) into the opponent's bottom, causing constipation, pain and/or embarrassment. It has no effect on unconscious targets. Witnesses that see the technique react oddly (Temari blushes, Pakkun questions if it's really a technique, and Gamakichi shows a look of disappointment), while those who have used or experienced the technique show great fear in it being used on them.

While seemingly useless, the technique can be quite useful if used properly. During the first bell test, Kakashi was able to throw Naruto a great distance, probably propelling him with chakra. Naruto would later find out that the point behind the technique was to target the opponent's blind spot, and when one substitutes their fingers for a kunai with an explosive tag, it can be a lethal technique. The aforementioned variant has only been used by Naruto.

Trivia

 * This technique's full name is.
 * The official name for this technique is Sennen Goroshi. However, the name is sometimes thought erroneously to be, meaning something along the lines of "Thousand Years of Pain".
 * This technique is modelled after the Kanchō, a Japanese prank of common usage among children. When Kakashi first performed it, it might have been a simple kancho with a technique-like name, which Naruto would believe to be a real technique, eventually leading to its usage in actual combat.
 * In chapter 5 of Rock Lee no Seishun Full-Power Ninden, Sakumo Hatake is said to be a user of the technique. At the end of the chapter, Kakashi, Might Guy, and Rock Lee perform a collaboration of the technique they call "Three Thousand Years of Death".