I just read a bit about his god with his huge, erect penis. Apparently, he originated in Asia minor and was brought to Greece by Greek colonists. He was popular with rural folk in Greece and then in the Roman empire, and even right into European Christiandom, being mentioned in the Canterbury tales.
Apparently he represents sexuality and fertility.
When I was in Pompeii years ago I bought a postcard depiction of a mosaic that showed a man with a huge penis. After some research tonight I came across more pictures of that mosaic and the explanation of Priapus.
I have heard of Priapus and also of a modern religious sect that does worship him.
It is called Eglise S. Priape, St. Priapus Church, founded in the 1980s by homosexual men of both Canada and America. In this religion, the penis is - As they say - the source of life, beauty, joy, and pleasure. It mainly involves phallus-worship which is accomplished through various sexual acts.
There are nine centres of the church in Canada and eight in the United States.
And just a important note: I have only heard and read of this, I have never had any interaction or even contact with this church.