The drag ruff is the 31st drum rudiment. A drag ruff consists of two double strokes before a single stroke. This is similar to the paradiddle rudiments, except that notes in paradiddle rudiments are played the same speed, where drag ruff notes are played at twice the speed as the context in which they are placed.
This rudiment can also be called a drag or a ruff. I was curious about the history behind each name and it led me to this wonderful article, titled Is it Ruff to Drag or Drag to Ruff? Watch a video demonstration of the drag ruff below.