The RPB or Relationship Pain Ball is an abstract object passed from one partner in a relationship to the other, and then to a different partner in the next relationship, and so on. The passing of the RPB is achieved by things like cheating on/insulting/beating/depriving the other partner. The true origin of the first RPB is unknown.
"Dude, I know she's been screwed up in the past but is it right that she cheats on me? It's terrible :("
"Looks like she's passed you the RPB!"