I see that the PRD has added a "Technology Guide." Perusing it, I noticed among the weapons listed is a Chainsaw. They left two important things off of the description. First a Chainsaw is +2 when used against Zombies. Second a Chainsaw is +20 and autocrits when used against Sharknadoes!
(My true opinion is that Paizo has truly jumped the Sharknado with this.)