. . . You mean SmackJeeves, right? xD
I'm not sure how to do the process, but it would require either sign-up or a birthday input pop-up (or just one of those simple pop-ups that say, "Are you 18? DON'T CLICK IF YOU'RE BELOW 18 ARGH").
I know the programming required for some languages, but not all. Which would you be doing this in? HTML/Java/etc?
EDIT: winglesscomic ninja'd me lol