Diane Keaton is no stranger to breaking new ground with her work. The actor - who turns 72 today - was an original cast member in the Broadway production of the musical Hair (1968). And she was in one of the earliest stoner comedies. Well, a stoner scene in a classic romantic comedy, to be more precise.

Before Cheech and Chong defined the stoner comedy subgenre with the premiere of Up in Smoke (1978), few American films touched on the subject in a non-sensationalized way (a la Reefer Madness type movies). Basically, there was the counter-culture classic Easy Rider (1969), a road movie exploring the cultural landscape of America in the 60s. And there were the x-rated Fritz the Cat cartoons in the early 70s.

Then there was Woody Allen's Annie Hall (1977), which certainly didn't endorse cannabis use - let alone legalization. But it did feature characters discussing the effect marijuana has on their lifestyles and their relationship in a mature, sensible manner.

Keaton's character Annie likes to smoke pot before getting in bed because it helps her relax enough to enjoy sex. But her boyfriend Alvy (played by Allen) thinks marijuana cheapens the experience by bringing artificial intimacy into the relationship.

The serious tone of the discussion is pretty groundbreaking considering that just a few years earlier, the American government classified marijuana as a substance that was as addictive and dangerous as heroin.

And the scene doesn't feature characters playing up the sort of stoner stereotypes that Cheech and Chong made famous. In fact, the wackiest part is the out-of-body experience that Keaton has while sober. Check it out.