"OMGZ," said Tegan, "we're both werewolves now due to convenient plot devices!"
"I agree, my sexually alluring sister!" Sara nods wisely, like an owl, or maybe some kind of older person who's been through a lot. "But now that we're werewolves, will you still love me? I mean, my legs will be hairier than normal!"
"Don't be stupid, I love your hairy legs the same way I love your lady parts - with all my heart and soul."
"Cool. Now let's sex. Because I bet werewolf sex is hotter than sister sex!"