Verb meaning to make something dull or uninviting sound interesting, like when talking to children. Teachers also diagnamate a lot.
Usually shown with exclamation marks in the written word.
Mother: "We're going to Grandma's house!! Isn't it so exciting?!?!"
Son: "Don't diagnamate, Grandma's house is boring."
Geology teacher: "Look at this amazing piece of granite!! Can you see how it has formed -really- slowly?!?!"
Student: "Sir's diagnamating again."