Sperg's Mother is a character that only appears a few times in the series. She even has a tattoo on her left elbow that says "Son," just like Sperg, who has the word "Mom" on his left elbow. She first appeared in "Ecto Cooler."
In Ecto Cooler, Billy made a poem about how ugly she is, and can make someone's face melt off right before she reveals herself to be a beautiful woman. But she did cause Principle Goodvibes too have his face melted off, but this could be from the power of her own, actual beauty.
- It appears, she looks more realistic than any other characters in the series.