I got to Woodstock on Thursday (day before it started) and was driving my '69 Dodge van through the festival grounds when someone from the crowd asked if he could hitch a ride on the open tailgate. I said sure, no problem.
About 2 minutes later someone shouts out "Colorado! You ripoff!
Next thing I know this guy runs up to the back of my van, breaks a bottle and sticks it very near to the face of the guy who was riding on the tailgate!
The guy with the bottle start yelling "I gave you my guitar and amp and you said you would sell them!". "I tried to get in touch with you and your phone was turned off!" I put the van in park, jumped out and said "What's going on here?" "Peace and Love, man - Peace and Love!" (which sounds really corny now, but it really worked then). They ended up making up....even shaking hands - if you can believe that - and walked away together. That was the only violent act that I witnessed at the the most beautiful 3 days of music, peace and love in the history of the 20th century.