Much like with my Headless Bride
, we started by making a duct tape dummy.
Have your male volunteer put on one of the turtlenecks and wrap his torso and arms in duct tape. Cut through the duct tape and shirt to remove it. You'll need to cut up the spine and cut down each arm.
Once it's off, tape the torso back together. Attach the Styrofoam head with more duct tape. Stick two bamboo poles into the bottom of the head. Cut the poles a little longer than the torso. The poles will help give the pirate some rigidity and give you something to help attach him to the backpack.
Attach the fake hand and pirate hook with more duct tape. You might also want to help secure it with a glue gun.
Stuff the torso with batting. Don't make it too full or he won't sit close enough to the mermaid. When it's well stuffed, tape up the bottom.