is a peaceful day in the underground, and you are seeing your adoptive mother picking blueberries, when she taste one, you see her skin became blue/violet she start to swell, swells tons of gallons of juice, her cheek start to fill, her legs and arms are sink in her juicy body, she check his body with her hands, until she became huge, round and bloated, Toriel was completely blue and immobile, all because she try a blueberry

Hehe, maybe I shouldn't eat that berry...