Part bunny, part vampire. Based off of a set of children's books written by James Howe following the life of a bunny vampire.
It also can be defined as a female who seems very sweet on the outside, but has a deadly bite once you get to know her.
Guy 1: Man that girl seems so sweet and nice!
Guy 2: She is until you start to get to know her. She is a lot more vicious than you think!
Guy 1: Like a cute little bunny with fangs.
Guy: A bunnicula!