In my opinion, Mark knows where M&M is, not because he’s becoming a hippie, but more because of the way he can get some drugs, since they are much present there. We can say that he was sincere when he told Bryon that he didn’t smoke, and it isn’t the first time he’s coming down here. One way to look at it would be that either he’s only wants to hang around or the other one, he’s involved somehow in the drug bussiness happening down there. If we think about it, he always come up with a way of getting some money and he doesn’t have a job. We can predict that either he is an intermediate in the drug business, or he is only involve somehow in that hippie house and it brings him enough money, and this is how he knew where M&M was.