As you're a journalist I'm surprised your first port of call wasn't Wikipedia
"The day's name originated in Philadelphia, PA, where it originally was used to describe the heavy and disruptive pedestrian and vehicle traffic that would occur on the day after Thanksgiving. Use of the term started before 1961 and began to see broader use outside Philadelphia around 1975."
So those people trampling over each other buying things they don't need are really pagans celebrating traffic accidents. I find that the more credible explanation as only Oxfam would operate a business where you only break even after the first 11 months of every financial year.