KUSA ZURIBIKI, Shaking Hands Act.
Or as the Japanese name cannot be properly translated into an English equivalent, we might as well call it the "Glad hand."
In order to secure a sudden advantage over an opponent, it is often best to resort to strategy and take your man wholly by surprise.
As a mode of attack, this act is one of the neatest, completest surprises known to the Gentle Art.
(1) A approaches B, holding out his right hand as if he were going to shake hands, grasps B's right hand as in ill. 1, and stepping back quickly, gives B's hand a violent pull, causing B to lose his balance and start forward, while A rushes back in the opposite direction, past B's right side, still holding B;s right hand, and stoops, grasping B's right ankle with the left hand, whirls B about and tips him over; or letting go with the right hand, sends him headlong with the left ankle, see ill. 2.
This is very simple and effective when you get it right.
From Jiu-jitsu: A Comprehensive and Copiously Illustrated Treatise (1904), p. 111-112, by Harry Hall Skinner.