Celebrities: a bunch of hypocrites! They all pay lip service to environmental issues like global warming. But most of them are heavy private jet users. They also engage in a smorgasboard of other environmental sins, from investing in oil companies (Madonna) to wasting water by demanding 120 bath towels at each appearance (Barbra Streisand) to various other transgressions you can read about here. But it's primarily the globetrotting use of gas-guzzling private planes that make their frequent entreaties to save the earth seem empty. So we're polling you, our readers, who have some of the most finely tuned hypocrisy detectors in the world: Which of these six "green" stars is the biggest environmental hypocrite? Cast your vote after the jump.