If an environmentalist invites you over for dinner, do not assume that your host’s primary purpose is to serve you a meal. The goal is education.
You cannot assume your host is vegan or vegetarian either. Doing so could lead to a number of social faux pas that are on par with or worse than calling them a Republican. While many environmentalists are vegan or vegetarian, others can talk for hours about how it is possible to eat meat and still be green. Their requirement of course is that the animal is raised on a small farm and allowed to run around and eat grass. If you are hoping to impress a host in the latter camp, tell a story about how you are raising a few chickens in your backyard. For extra points, use the following terms: free-range, factory farm, and antibiotics.