How to tie a Constrictor Hitch
Repeat the first few steps of a Clove Hitch as normal.
Do not pull the knot tight yet. Pass the working end (green end) over the top of the first turn.
Now pass the working end under the first turn as shown. Pull the end through.
Pull on the working end (green end) and the standing part (long end of the rope) to tighten the knot.