You Got Your Exposition in My Argument

A main character, likely the Narrator, walks into a heated argument between at least two lower-downs. They both turn to the hapless bystander, trying to get support in the spat by yelling over each other. Expect something along the lines of, "Slow down and tell me what happened, one at a time," followed by two (or more) chunks of exposition. These will always conflict greatly.

In visual media, will often be accompanied by flashbacks from the perspective of each. Particularly in animated works, these may make use of completely different art styles to exaggerate the schism between the two versions of past events.

Note that this is only an expodump when the bystander (and thus the audience) is unaware of what caused the argument, and when it is a setup rather than the main plot.