If your community only contains occasional sexually explicit or adult material, such as the occasional nude photograph in a photography community, it is generally not necessary to restrict membership. However, these entries should be placed behind a lj-cut tag and clearly contain a warning that they should not be viewed by minors.
Regardless of the purpose of your community, all community maintainers are responsible for verifying that any individual posting images of him- or herself is over the age of 18 if any of the images being posted contain full or partial nudity, or are designed to arouse, provoke, or otherwise sexually stimulate a viewer. Any image of someone under the age of 18 who is nude or semi-nude, or designed to arouse, can qualify as child pornography and is not permitted on LiveJournal's servers. If your community is designed for users to post pictures of themselves, you must make sure that you follow these restrictions.
Basically, it's like this. If you post nude pictures they ALL must be in a friends only post, under an lj-cut with a warning (i.e. Not Work Safe). I'll have to check to make sure any dreadheads who post nudes are over 18 by checking their user infos. I'll bold this so there are no mistakes.
If you post a nude picture and you do NOT have a birthdate in your user info or you are a minor, I will delete the post. If you continue to post without a birthdate or if you are a minor, I will ban you.
I hate to do this but if I don't this whole community could be deleted. I don't want that and I'm sure you don't either. So far, everyone who has posted has been legal age. Keep it up. No kiddie porn. And play nice. No making fun of the nudies or they might run away. And then no one gets dread porn.