Pretending what would happen if you said something really rude or nasty to someone, or if you did something pretty mean or dissed someone on paper in someway.
An example of whatiffing I did today, while typing up a paper:
The world needs to find more fair solutions to the growing environmental situation. We need to look for solutions that are not harmful to the environment, and to try harder to harvest reusable energy. This is some serious shit and we gotta watch our backs ya heard me fat bitch?