Complex sentence: The Sumatran Rat Monkey, (least according to a zoo custodian in the film) is the offspring of small tree monkeys and giant plague rats scurried off passing ocean liners, swam to shore, and began raping the monkeys.
Split into simpler sentences: The Sumatran Rat Monkey, according to the film, is the offspring of tree monkeys and giant plague rats. As a zoo official states in the movie, the rats scurried off passing ocean liners, swam to shore, and began raping the monkeys.