This is more commonly known in the Sex Party & Pornography scene as a Cox Knot. Cox Knots Rule!!
"At the party last night, Adam had Rebecca in a mexican headlock on the sofa for like 8 minutes! It was killer!"
"Do you mean a Cox Knot?".
"Nice One! She'll be shitting cum for a week!"
A sexual position whereupon the woman lies on top of the man, on her back. He enters her anus in a reverse cowgirl position, then she lies back and he pulls her legs high up around her head with his forearms, and links his hands behind her head. This forces her head forward and her legs back uncomfortably, in the "mexican headlock."
Dude#1 How did you get on with Candi last night?
Dude#2 Awesome! She was just as adventurous as she is on screen - I even managed to get her in the mexican headlock!