The tiny shrine dedicated to a Chinese goddess, Chao Mae Tubtim, is one of the more unusual sights of Bangkok. It's located in the grounds of the Nai Lert Hotel, which is now managed by Swissotel.
The shrine was originally set up by "Nai Lert", one of Bangkok's first property developers who developed the area around the shrine in the early part of the twentieth century. Tubtim (or Tuptim) is a Chinese goddess usually prayed to for the protection of sailors. There's a small statue of the goddess in the spirit house that is found in the area of the shrine.
But, what interests most people who visit the shrine are the wooden and stone penises. The shrine is probably the largest phallic one in Bangkok. The phallic offerings aren't normally associated with Tubtim, but the story goes that one or more women got pregnant after praying to the goddess, and in 'thanks' she left the phallic offering, called a bhalad khik in Thai. More people starting leaving the offerings, and not just for children, but for anything.
The shrine is located right on the banks of the canal, behind the hotel. From the front of the hotel, take the stairs down to the parking area and walk back to the very end of the hotel area. You can also reach it via the back entrance to the hotel grounds, which is a slightly shorter walk from the Chidlom Skytrain Station.