Not to get in the way of the struggling attempts at intellectual eliteness by TA, but now back to the original question.
Wes and The Beef are correct. One arm at a time, curling inwards along the body and than lowering in a gooseneck position for the forearms. Confirmed that it was used quite a bit by the Muscle Beach crowd in the '60's/'70's by an old timer of that era. I had know it as the Zotterman curl, so I am corrected on that part.
Mild suggestion to TA: time for you to gain about 25lbs of pure muscle mass, would not you agree? If that is your goal. The high school gymnast look is gettin pretty old after so many years at GetBig, do not you think? No offense, but you tend to look small and fragile. Sorry, no malice intended, just a personal observation on my part. Good Luck, you may need it.