There was a purple party @ Cal. I arranged it About 50 people attended including some player's parents . It was low key with no commitment to attend, just show up, build your pizza and buy your beer
The 1967 Opener against Miami was the game I remember. Miami was preseason#1 NU's game plan was to run directly at "The Stork"(Ted Hendricks) to negate his mobility/pursuit
The Cal game gathering was a purple party not a Purple Party