Actually, there are a number of them, but here are four examples.
Why is it assumed that when vegans get sick it's because of what they don't eat, yet when non-vegans get sick it's not assumed to be because of what they DO eat?
Why are vegans often asked if they support abortion, yet pro-life folk are rarely asked if they support ALL life? A surprising number of anti-choice proponents favour capital punishment, for example, yet this isn't often thought to be hypocritical even though the hypocrisy charge is lobbed against pro-choice vegans all the time.
Why are humans murdered while other animals are killed -- it's the same action with the same consequence is it not?
And lastly, why are vegans routinely accused of being judgmental, but non-vegans who judge the lives of other animals as less important every time they stuff them in their mouths are not? Eh, tell me that!
I stole the awesome cartoon above (don't remember from where now), but it's from the talented Vegan Sidekick who also has his own website where you can find images in categories (how cool is that?), and books (which I may just have to buy), so go give him some love! Seriously, right now. No point in waiting. ;)