Well hopefully they are coming from a Search Engine, and I guess they haven't had a warning there, even though they can see in the SE that it's a porn site from the text + they shouldn't get my site in their results unless they search for some porn keywords
OR they might be coming from another adult site that links to me.
Conclusion: I don't think I need a warning page O_o
But then again, it's extra ad space...think I will have to sleep on this one or see some more opinions.