Cameron Diaz was a guest on The Tonight Show with Jay Leno last night — and the actress/environmentalist was keen to share her green passions.

She explained: "It's one of those things that is just a lifestyle choice. I was brought up that way so it's something that I automatically do. I'm rigged that way."

Regarding green flushes (in what was obviously a pre-discussed question with Leno), Diaz said, "I do follow the, 'If it's yellow leave it mellow, if it's brown flush it down' saying. I believe in that 100 per cent. But there are a couple of rules. You can't go more than two or three times, if it's consecutive, if you're drinking a lot of water, without flushing. But if you have coffee or something, it's going down."

Of course, people remain shocked to the whole concept of conserving water in the bathroom with this method — but it's great to see Diaz sharing anyways....