Don't have to be an actress. Could be a female singer, news woman, etc. Just so they are famous.
Someone posts a picture or GIF of a famous woman. Then someone else posts what they think is a better picture or GIF. If someone posts a picture the person trying to do better must post a picture also. Same goes with a GIF. Then that person just names some other woman and someone will post a pic or GIF of that woman. Then someone else will try to post a better one. Hope I explained it OK. I will start. This first one might be tough because I think it is her best GIF.
Now someone tries to post a better GIF than that. Then name someone for two others to try.