Allison Biggers

Julia, a teacher in a school for the deaf, has a hideously deformed and deranged twin sister that resides in the local loony bin. She escapes to gate-crash a surprise birthday party for Julia by murdering all the party guests with the help of a giant killer Alsation dog, which gets it's comeuppance when lobotomized by a power drill, in a scene that will offend most animal lovers. (imdb)