I am Mama Hippo because my DS has been "Baby Hippo" since he was born. When he was a newborn and he got hungry, if you put your cheek up to his mouth, he would open his mount REALLY wide and shake it back and forth, like a hippopotamus. He was also just ravenous for milk cus he was so small at birth (5.5 lbs). We'd say, "Uh oh, looks like we have a hungry hungry hippo!" He's pretty chubby now, so he's still my baby hippo.
Its cute, his little cousins (age 5 and 3), whenever they find anything with a hippo on it, they give it to DS.