If you live in San Francisco, simply walk up and down Haight for a while (near Ashbury, of course). Look for "street characters" - every once in a while as one

If you live in San Francisco, simply walk up and down Haight for a while (near Ashbury, of course). Look for "street characters" - every once in a while as one of them passes you, they'll quickly call out "hey man, wanna buy shrooms?" and keep walking. The expectation is that if you want to buy you'll go shoulder tap them.