Penis-shaped cupcakes or cake is always a fun thing. One of the funniest things I ever saw at a bachelorette party was a pinata. It wasn't penis-shaped.
What a friend of the bride's had done was taken a pinata shaped like a person, and cut off the paper "clothes" it had. Then she took some paper of her own and put a little g-string on it's butt and assless chaps. Then she pasted a picture of the groom's face on it. We were almost laughing too hard to hit it.