Age Gate for specific threads?

[jribz]

Maybe this is already out there, or there is a simple way to do it without a mod...

I'd like to be able to post an age-gate type interface, it can use vbulletin's birthday if needed. I want to be able to limit access to posts / threads for people under 18, on a per post basis ideally. I know I can password protect a forum, but it really needs to be an age gate for legal reasons.

I run a video game site and some trailers require that there be an age gate. Anyone have a suggestion or know of a mod that will do the trick. I searched for age gate but no dice.

Thanks in advance.