Deploy the Reductio ad Hitleram
"Hey, you're a vegetarian! Has anyone ever told you Hitler was too?" (They will have heard this. All too frequently.) The veggie will probably respond by telling you that this is an urban myth and that Hitler did occasionally eat meat. In fact, the urban myth is literal fact, as we know from Hitler's Table Talk. Not only did Hitler think that vegetarianism was doing the "right thing" by the animal kingdom (Hitler was a leader in "animal rights"), but he was certain that the future belonged to vegetarians. The real urban myth is the veggie's fanatically spread tale about how Hitler really wasn't a committed veggie.
I don't even know where to start. Unnecessary contempt for healthy eating? Oh, maybe the Hitler thing. Conservatives are pissing themselves over the fact that they never make a Hitler or Nazi comparison in the face of endless video and audio clips being thrown in their faces. Perfect time to pull out a Hitler reference!
Now let's get stupid. Let's take an irrational hatred towards "dirty hippie" vegetarianism and make the assumption that your target vegetarian is a liberal. Now take that dietary health choice and equate it to the mass murder of millions of innocent people. Awesome.
By taking this position - and you know some mindless goons will - conservatives will do one thing and one thing only: confirm that they are hypocritical monsters incapable of the very basics of logical thinking.
But hey, they got in a jab at that dirty veggie, didn't they? w00t! Hitla represent!