Atamahane 「頭跳ね」 is more known as the "head bump" rule. Sometimes, more than one hand in tenpai may be waiting on the same set of tile(s). If one happens to be discarded, variation allows each of them to claim a win simultaneously. With atamahane, only one is allowed to win the hand. All others are "bumped" and denied their hand.
The most common rule to atamahane grants the win closest to the discarder, in relation to the wind order. For example, if West discards a winning tile, the North is first in line for the win. Other rules will grant the opposite, where the further player from the discarder claims the win. Once again, if West discards a winning tile, North may be overridden by another player down the rotation and instead claim the win.
- Epic Mahjong Fail (YouTube)
- Triple ron video from Janryumon
- Atamahane scene in Akagi.