Kani-basami (蟹挟), the crab scissors.

Nage-waza (throwing techniques), Yoko-sutemi-waza (side sacrifice techniques).
Required for: 4th Dan (black belt, British Judo Association); 5th Dan (black belt, British Judo Association).
Also known as: scissor takedown (english).

About
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A sacrifice throw in which tori leaps sideways and scissors uke's body between both legs, one across the waist and one behind the knees, felling uke like a cut stalk. It is documented here for recognition and history only: the technique is banned in competition and should not be practised in randori.

Key points
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1. Recognise it: both of the attacker's legs leave the mat and scissor the body
2. Banned in competition; attempting it is direct hansoku-make
3. Do not practise it in randori; the falling scissor risks serious knee injury

VI judo notes
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Recognition only, and worth knowing from the receiving end because it arrives with no warning at all: a leg across your middle and another behind your knees in the same instant. The danger is to the leg you are standing on, so go down with it rather than resisting on a planted foot, and report it however it was meant.

Reference pages elsewhere
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Kani-basami on the IJF technique reference (International Judo Federation): https://judo.ijf.org/techniques/Kani-basami

From Waza Book: https://wazabook.com/techniques/kani-basami/