Fertility Gods

The fertility god Priapus is easily recognized by his huge and erect phallus. However, according to myth he had originally been cursed with impotence because his mother, Aphrodite, meddled between Helen of Troy and Paris. Frustrated by his impotence and overcome with lust, Priapus tried to rape a nymph, for which Zeus punished him by bestowing on him a huge, permanent erection. 

Witchcraft

Ancient Egyptian tablets describe how to curse someone with impotence. Medieval scientist Albertus Magnus wrote that taking a piece of paper with a man's name on it and tying it to a wolf's penis would make him unable to have intercourse, until the paper was untied. In the 13th and 14th centuries, witches were accused of causing impotence. Even in recent times, men in the Congo have claimed that "penis snatching" sorcerers have cast spells on them, making their genitals shrink or causing impotence.  And as recently as 2008, a woman in Saudi Arabia was executed for using witchcraft to make a man impotent.

Incantations

Egyptian papyrus scrolls advised men to apply a poultice while reciting, "Be erect, be not soft, be strong, be not weak." Likewise, Babylonian texts suggested that a woman do the honors of anointing the penis with an aphrodisiac concoction, while chanting, "Let his penis be like a stick of martu wood," and, "Let a horse make love to me."

Voodoo

Voodoo has been blamed both for causing impotence and curing it. Although traditionally voodoo has been associated with West Africa, Haiti, or New Orleans, in 20 B.C., the Roman poet Ovid speculated that his impotence was caused by someone sticking needles into a wax figure of him. One voodoo spell to render a man impotent calls for taking a piece of material with the man's semen on it, tying stones in it, and throwing into a body of water. A specially prepared powder could also be slipped into a victim's drink to induce impotence. If the potion worked, it's impossible to say whether it was due to the ingredients or to the power of suggestion. Fortunately, there are ways to reverse the spell. According to one source, a man may cure himself by peeing down the blade of a knife so the urine flows onto the ground.

Rituals and Festivals

Is the fertility rite known as May Day the origin of modern pole dancing? That's a bit of a stretch, but the maypole is considered by many to be a phallic symbol. The wicker man, a straw effigy burnt during the Celtic or pagan holiday of Beltane, is often depicted as having an erect phallus.

Less ambiguous are the phallic festivals of Japan, which feature processions with enormous penises. Think "Oscar Meyer weinermobile", but with a huge penis instead of a hot dog.