Just suggest your website to whichever one category is the best fit in your opinion. If the editor doesn't agree but the site is listable, it'll be moved to a more appropriate one.
I understand your question a little different than jimnoble has answered.
Adult sites may only be suggested under
http: // dmoz . org / Adult
(combine the parts of the url)
and find what you think is the best subcategory in this part of DMOZ.