Eye Color change? 10 points?

I have brown eyes, well, 75% brown and 25% hazel, they've changed slightly. But i also have brown hair and tan white skin. I do like my eyes, but I want to accentuate and/or change my eyes to green temporarily. How can I naturally, easily, and temporarily change my eye color to green, or really bring out the green in them, wirhout using contacts? Thanks!