The Legend: There was a brown-colored LSD at Woodstock that caused many people to have bad trips.
Status: Most likely false
Drug use was prolific in 1969. As the Woodstock story goes, in the midst of the 3-day music festival, the medical tent was overwhelmed with concert goers having adverse drug reactions. It has been reported that nearly 800 Woodstock attendees sought medical attention for drug-related problems, and one person even died from their drug use. The problem was traced to a specific drug and announcements were made from the stage to "not take the brown acid."
What is brown acid? LSD is often put onto blotter paper that is adorned with colors and sometimes extravagant artwork, everything from Disney characters to psychedelic patterns. Long before Woodstock, myth had developed about the quality of the LSD based on the color or artwork of the blotter paper. For example, the blue acid might give you more of a body trip, while the red might give you more of a head trip.
In reality, acid is acid. There is little variation in the actual chemical properties between batches of LSD. However, user expectation is a significant determining factor when predicting the quality of the trip.
Was there really bad LSD at Woodstock? There may have been a bad batch of blotter treated with something other than LSD. There also might have been people happily tripping on brown acid until they heard the warning, and then their trip became a bummer. But the LSD was probably all just about the same, no matter what color blotter paper it was on.
In the end, there were three documented deaths at Woodstock. One from a heroin overdose, one person was run over by a tractor while he slept in a sleeping bag, and a third person fell from some scaffolding. No one died from the brown acid.