Actually the first time I heard of marijuana or "ganga tea" was with Jamaicans. I read that marijuana tea is a common thing there. I just haven't found any specific info on how Jamaicans make it.
Here's some info on marijuana tea in Jamaica. The tea is made from the younger plants: " On a recent trip to Jamaica, I discovered that drinking cannabis is looked upon completely different than smoking it. To my great surprise people of whom I knew that they were strongly opposed to smoking ganja and had never smoked it before, turned out to drink ganja tea (almost) daily. Sure, I knew that ganja tea was often used as medicine, particularly in the countryside, but that drinking ganja occurred to such a large extent was new to me. Many people who I had known for a long time and had always considered non-cannabis users (among them grandpas and grandmas in their 70s) turned out to start off the day with a glass of ganja tea! However, ganja tea is not made from the same, ripened and dried plants that are used for smoking. Ganja tea is drawn from the young, green plant. Many Jamaicans drink ganja tea - to which they attribute various healing and prophylactic qualities - as medicine. The tea is said to make the body strong and less susceptible to illness. It is also often drunk, if someone suffers from a fever or a cold. Furthermore, ganja is said to be a good remedy for stress...." http://www.rism.org/isg/dlp/ganja/analyses/solinge4.html