I remember when Green Bay lost to the college all stars in 1963.
I watched the game with my gang of junior high school friends. I think it was a night game at Soldier Field in Chicago, and we had a sleepover at my house.
We were in total shock after that loss because Green Bay played most of its starters for the whole game.
I remember watching what I believe was the last of these exhibition games, when an incredible downpour occurred, washing out the game. The game was summarily called, and that was the end of that.
... I find corroboration on the web that this was in 1975 with the Steelers vs. the College Allstars. I don’t actually see video of the terminal downpour, though. I don’t know why, as it was riveting. The rain actually obscured the lighting, and the commentators in the booth were in fear for their own safety.
And in Jerry Kramer’s book “Instant Replay” he describes how Lombardi was in a rage at the Packer’s players after that embarrassment of the NFL’s championship team, losing to a bunch of rookies who’d never even played together.