"To reef", is a sailing term which means to lower or bunch the sails up in anticipation of a strong and dangerous wind.
It would require pulling on a rope which would have been made of hemp (oh yeah, same stuff, it made good rope as well) thus the terms "reef the sails", or, "reef her up", or even cowboy slang meaning to jerk harshly on a rope when team roping.
Reefer as far as convenience store Coca-Cola goes must mean a refill, hardly as colorful a term.
Talk about dumbing down.
Once the rope goes around its horns, reef it up and get your dallies in.