On the first Sunday of April each year, a very interesting festival is held at the Kanamara Shrine in the Kanagawa Prefecture in Tokyo. It's known as the Kanamara Matsuri, or Festival of the Steel Phallus.
The festival dates back to the Edo period(1603-1867), when prostitutes would visit the shrine to pray for good business and protection from syphillis. At this time of year they would carry an image of the shrine's phallus around the streets.
Today the Kanamara Festival is a fertility festival (and after visiting I have to admit I'm feeling especially fertile) and it also used to help to raise money for HIV research.
The festival started with maiko(trainee geisha) dancing on a stage. This was then followed by the mikoshi(portable shrine) with phalluses on the top being blessed. After this they were then carried through the streets of Tokyo. In fact one of the shrines(the big pink one) was carried by a group of transvestites. If you want to you can even join in carrying the shrines if you like (a dress is optional).
If your easily embarassed it's probably not your thing, but from what I could tell everybody had a great time. I think the great thing about the festival is that it shows what a wonderful sense of humour Japanese people have.
If you want to you can also buy penis shaped sweets.
People also carve out penises from various vegetables such as carrots or radishes. These are later auctioned off to the highest bidder.
One of the funniest things to happen was when I was having my photo taken on one of the huge wooden phalluses that you can sit on. Just as my picture was about to be taken, an old lady walked up and put her arm on me.