There was a scene from "Fast Times at Ridgemont High" where Judge Reinhold was working at a burger place and was talking to a new guy who just came from another burger joint and they were comparing "secret sauces."
https://www.youtube.com/watch?v=WOM6Zd5oUsg
The one urban legend that will soon come true is that McDonald's Hamburgers are made from worms.
In the 90s I worked in Chino CA near many diaries. My boss lived locally and knew the dairymen. Supposedly the fast food chains ordered the quality of meat in this order best to worst:
Carls JR
In N Out
Burger King
Mickey D
Jack N The box
This is from the 90s.