It may be the reason Midwesterners call soda "pop"
There may be some element of hearsay to this one, but it still sounds better than half the nonsense your uncle Bob cooks up about Area 51. Fact: back in the day, Green River bottles weren't capped. Instead, there was a marble inside each bottle, used to stir the syrup that would settle on the bottom of the drink. To seal the bottle, one would flip it over, the marble would fall into the neck of the bottle, and the carbonation would keep it pressed in there. In order to open a bottle, one would jerk it up and down, and the marble would fall out of the neck. Theory: when the marble fell out, it would make a popping sound, hence why people started calling Green River “pop.” Again, we can’t really prove this, but some people think that gravity is just angels pulling down on your pants when you jump, and this seems to be more believable than that.