The Triangle Choke

It's a known technique in judo as well. The triangle symbol, represented on many BJJ logos.
The triangle choke applied with the legs and it cuts the blood flow on the neck causing faint.
The application is based on wrapping one leg around a neck and the other on an armpit. The legs closed at the ankle under the knee bend. Essential to pull the arm across to be effective.

It has multiple variations like inverted triangle

Ryan Hall has an instructional DVD about the triangle

Wide variety

- pull the head down,
- put the hand under your armpit and apply an armbar during the choke
- anchor the leg with one hand to prevent standup and a following slam

from or into omoplata

unconsciousness, sore neck

- Either both your arms should be inside or both outside.
- If it's not closed properly, heads up and try to elevate from it.

In the Lethal Weapon movie, the final fight ends with this submission applied by Sgt. Riggs on Mr. Joshua. Lethal Weapon triangle choke