How to tie a Sink Stopper Knot
Make a crossing turn. Now make a bight and pass it through the crossing turn (Just like for a Slipped Overhand Knot).
Tighten the crossing turn by pulling on the bight and the working end.
Finished Knot
Hold the know with one hand and pull on the standing end with the other. You may have to work the knot into shape a little.
