Reefer goes further back than the 1936 movie that popularized it: Reefer Madness. Some say that reefer was a sailing term.
The reefer on sailing ships was the man who folded the sails up in a shape that, some say, looked like a joint. Others argue that reefer comes from the Spanish term grifa, which means marijuana.
Reefer grew in popularity in the 1920s and 1930s but became known nationally when Reefer Madness, a movie about the dangers of marijuana, became an ironic hit in the 1970s legalization movement.