Yippy Skippy, The Evil! is the fifth Sluggy Freelance book. Notable topics include Kiki's virus, a nanite infestion created by Dr. Catherine Crabtree and the return of old Dr. Schlock, Gwynn using magic again to disastrous consequences culminating in her leaving and getting possessed by a portion of K'Z'K, a date between Torg and Zoë that is interrupted by the return of Oasis and Oasis' second death, and the first appearance of The EVIL.