Well folks, The reason why Cookie Monster becomes Veggie Monster was due to a very sad dream. You see, On a Sesame Street sketch, Cookie Monster decorated for a birthday party. He found a birthday present. It was full of Cookies. Cookie Monster ate the whole box, And there were none left for the birthday party. Cookie Monster had to take a nap and think about it. He snoozed in to dreamland. In his dream, He saw a most humongous cookie he has seen. But it turns out that the cookie speaks. He addressed to Cookie Monster as "Monster Cookie." Cookie Monster wonders why he is called "Monster Cookie." It was very sad story. He was once a blue furry monster. The food he had mostly was Cookies. He rarely eats carrots, fish, and whole wheat bread. But mostly cookies. Since, He had too many cookies all the time, His fur was braked into chocolate chip, his brain was transformed into cream filling, he leaves crumbs whenever he walked, And before he notice it was too late, He was transformed into a cookie (Very sad). When Cookie Monster wakes up from his dream, he sobbed "What a dream! Oh, Very sad!" Cookie Monster learned his lesson. And started to eat healthy treats (Carrots, Fish, and Whole Wheat Bread). And then, He eats a cookie and says to the viewers "Well, Maybe sometime a cookie."