These are all facts ( or fiction? ) taken from the sidelines in the Dr.Slump manga. I have no idea if these are true or not. Toriyama wrote in the manga that it is, but he could be just joking about it.

About Toriyama:
Throughout the manga Toriyama usually state a few facts about himself. He lives in a rural area in Japan. The origin of Dr. Mashirito:
Dr. Mashirito is actually his editor, Torishima. It started when Torishima rejected Toriyama's manuscript because he thinks that Senbe's rival enemy does not look nasty and wicked enough. So Toriyama tried to think of a different image when he thought " Who in this world is wicked and nasty?" and drew Torishima in his manuscript as the evil scientist. When Torishima saw it he was so angry but since it was close to deadline Torishima could not reject the manuscript. So Dr. Mashirito was created. Sometimes in the manga Dr. Mashirito would say " Manuscript rejected" but if Dr. Mashirito's caramel-man are winning he woul say "