This thread is another reminder that there are too many people out there who think that the human body is some sort of predictable machine... reduce this, and it helps that... cut back on that, and it will help you with this.
The human body is an active system that has many means to keep itself self-regulated. One time activities such as pot smoking or drinking a cup of green tea, or whacking off are, on paper, known to have certain effects on certain hormones. HOWEVER, one must not forget that whilst one may partake in certain habits, hobbies, or routines, the human body is actively counteracting the effects by doing whatever it has to do to keep itself in hormonal balance.
That being said, although one particular activity might be shown to, say, reduce DHT, one really does not know how this will ripple through the system and what effects it will have. Sometimes, some substances said to quote "reduce DHT" only result in the body converting the excess free testosterone into estrogen, resulting in some very unfavorable side effects. Other substances might quote "reduce DHT" but only result in the body adapting to this and increasing the rate of testosterone to DHT synthesis to compensate.
Only chemicals that have been proven by the FDA to reduce DHT AND keep this reduced DHT environment stable over a period of time are worth talking about.
In a nutshell, don't speculate or experiment on anecdotal evidence. Rely on proven products that have been shown to have a real and positive effect on male pattern baldness.
That being said, I must admit that I really enjoy the occasional joint. Marijuana is far less damaging on the human body than is alcohol. Alcohol causes morbidity in most all internal organs of the human body, and when one uses alcohol in excess and goes to sleep or passes out, it induces the body to enter a state more similar to a coma than sleep... whereas marijuana inflicts FAR less morbidity and damage to internal organs of the human body. And, when one 'overdoses' on marijuana and 'passes out', the state is far more similar to sleep than the coma-like effect that alcohol creates. Alcohol, in excess, depresses the most central nervous system functions of the human brain. Neither substance is good for you, but if given a choice of the two, marijuana is preferred in my opinion.