A person who considers himself or herself to be an environmentalist. However he/she does not actually have the environment's best interests in mind. Typically a naive college student who doesn't really know what they're talking about, they just think environmentalism sounds cool. Because they do things that hurt the environment, while claiming to be environmentally friendly, their claims are invalid. Are also known to drink Starbucks, eat vegetarian at McDonalds and opinionated about things they know nothing about.
Yesterday Veronica was lecturing me about turning the lights out after I leave the room because its bad for the environment, but today she took at 30 minute shower! She's such an invalidmentalist.