One thing that's tough to guess about the nut found inside the sort of shell Georgia O'Keefe would've found inspiring is that it's very good for penises. In fact, it's the only aphrodisiac on this list that is also a natural cure for erectile disfunction. According to the American Pistachio Growers, men who ate about 3.5 oz. a day saw improvements in performance after just 3 weeks. Why the Pistachio Growers are testing and treating men for erectile disfunction is questionable (the song "Sex Farm" comes to mind), but the nuts speak for themselves.