Mama Luigi is the identity Luigi takes after giving birth to Yoshi's egg. While initially confused by the sudden appearance of Yoshi's egg, she quickly discovers her mother's instincts and raises Yoshi to be a big responsible dinosaur. She later gives birth to a couple other children and they all live happily ever after.
The mamafication of Luigi took place somewhere in Dinosaur World. While peacefully walking through Dinosaur World, Mario, Luigi and Princess Peach stumble upon a place called Dome City. Upon entering the city, a pack of dangerous reptilian creatures suddenly appear out of nowhere and attack the threesome. Oh, and there's also a blackcock flying around. Luigi is separated from the others and is attacked by a really fat reptile which causes an earthquake by moving its feet. A fissure is created and Luigi unpreventably falls into it. After falling for a couple hours, Luigi spots a P-Balloon, commonly known as a "Magic Balloon". Luigi manages to land on it and its pregnancy-inducing magic activates, instantly implanting an egg into Luigi's magically created womb. (more...)