Pretty sure we call it Renko Ho, or Gooseneck comealong (although I think it actually means "arresting technique"). The application would be like you would fake a "hammer lock" from the side/rear. Uke, and most people will pull their arm out and you just scoop it up, right into Renko Ho. Am I getting it?
Close, but nage's arm winds up a little more on top and to the side, instead of on the bottom. I'd love to be sure to have the proper name for the technique.