One night in 1970, daredevil Evel Knievel was preparing to jump his motorcycle over 11 vehicles in front of a packed stadium in San Francisco. Apparently, jumping a motorcycle over a fleet of cars in a confined space wasn't quite butch enough because Knievel also decided to start an epic brawl with the Hell's Angels.
This wasn't long after the disastrous and deadly Stones concert at Altamont, where Hell's Angels were loosely hired as "security", resulting in multiple fights and a murder. Tensions were compounded by the fact that Evel Knievel hated the Angels' nihilist thug behavior anyway. The most significant contributing factor, of course, was that one of the Angels threw a tire iron at Evel, a man who took no shit.
"I always wanted to punch one of them anyway. So I rev my motorcycle up and I threw it into a slide and I knocked this guy piss over teakettles. All of a sudden, about 500 people jumped out of the grandstand and grabbed these 4x4s and these 2x4s and they absolutely beat the hell out of these Hell's Angels"– Evel Knievel, YouTube