I not knowingly when i was little kid did a thing similar of a dropping waki gatame as a little kid when i felt threatened (if I understand the concept of dropping waki gatame correctly)
was never taught it, i just acted instinctively. (Cradle the arm like your escorting a women politely, but lock it up tight and drop to your knees)
person came to school the next day and aparantly I almost busted the arm
Grade 4 jitsu!