Artemis BJJ (MYGYM Bristol), Open Mat, Bristol, UK - 02/02/2016
I'm writing this up a couple of weeks after the fact, but checking when I put up pictures on Instagram, this was the open mat we went through the armbar grip break. They are linking their hands to prevent the armbar (I don't think this grip break works as well if they are grabbing their elbows, their collar etc). Your arm nearest their head goes under their arm. You bring your other arm over, so that your elbow is against their elbow. Clasp your hands together, then twist out. It's hard to visualise from text, but hopefully the picture below makes it clearer.
Matt referred to this as the Nutcracker: I'm still trying to think of a logical judo-esque name. Best I've come up with so far is cross arm clasp', but I'll keep thinking. Any good suggestions welcome. ;)