It was the Kanamara Matsuri (Penis festival) in Kawasaki! It's centered around a shinto phallus shrine where prostitutes used to pray for protection from sexually transmitted diseases. Nowadays, it's mostly become a tourist attraction, as well as an excuse to get dressed up in a ridiculous costume, including a penis box, a blow up doll, or a samurai, and drink lots of saki, beer, and shochu.
There were also phallus images absolutely everywhere... on the flags, shirts, souvenir glasses, lollipops, and carved vegetables.
The temple resembled a regular temple with lots of tori gates. They had a drum performance and a karate group put on a show half way through the day where they broke boards with their feet and hands.
Everyone joined in the festivities from the old and peverted to the young and innocent. Fun for the whole family!