How should I build an age verification form with php session?

I开发者_JAVA技巧 need what seems simple to me, but I can't seem to find it online.

I need a user to enter their birthday and for the action on a form to be effected one way or the other. I would also like a session to be set but thats optional.

I know that age verification is lame but its an alcohol company and it has to be there.

I am good with html/css but not stellar with jquery or php...

Thanks so much

The most entertaining age verification I ever saw was the first Leisure Suit Larry, a series of primitive graphical adventure games. It would ask culturally-based questions that would be instantly known to older players, but kids would not (usually) have a clue. Like:

John, Paul, George, and
a) Joseph
b) Samuel
c) Ringo
d) Malcom

To successfully enter the game, a potential player has to answer three such questions correctly. It would pick the three questions at random out of a database of maybe 25.

Obviously, this does not directly answer the question, but perhaps it will inspire a more creative solution than asking a birthday. (Like that could not be circumvented.)