I don't think this has been done yet, and I am surprised.
The point of the game is to post a picture. The next user must caption this picture, then post another one. The picture can be of anything as long as it has no caption-like text in it and is not inappropriate. The caption can be a description of the situation in the picture, what a character might be saying, etc. Use as little cursing as possible. Otherwise, have fun posting!