Some of the avatars are not visible to me. They just say "pea name" avatar. One example is "maryland" and "2xmom". I checked and there are others. If I right click on the avatar and then click on view avatar it goes to a (maybe russian?) porno site.
It's for any accounts that don't have an avatar. There is no avatar or image to be seen for those accounts.
It appears to me that it's coded to put a placeholder image there instead which is linked to a website that at one point, would have shown a placeholder image, but now it doesn't exist and someone on the internet - not 2peas - have redirected it to that porn site.