Why do SOME adult vegans  call people that eat meat names?

because they are tired of the anti-vegan movement

Why do SOME adult Vegans  call  people who eat meat  names ? i suspect  the question infers  "DEGRADING or negative terms "   i suspect the same reason Donald J Trump  uses  his big twitter  account and Strength of  the PRESIDENTIAL  OFFICE ( which is in decline  in the  eyes of  many of  the other countries in the world  since he habitually  tells distortions  DEGRADES  other  people and countries ( SHITZ HOLES )  and has a affinity  for DICTATORS  his pals like Putin )  "AMERICA'S WORD is no longer trusted  )     to DEGRADE and  socially belittle and an attempt to  INTIMIDATE  other ... aka a BULLY  psychologically it is believed  that people do such behaviors as a COMPENSATION mechanism  to distract from their own  deficiencies   Bullying is not typical aggression  it is INTENT   the DELIBERATE  attempt to cause  HARM  to those of lesser power  BULLIES are made not born  the learned behavior can begin as early as age 2   the child learns early  that they GET WHAT they WANT  at least the FIRST TIME  RESEARCH finds  that BULLIES lack pro-social behaviors are untroubled by anxiety and do not understand other peoples feelings and view THEMSELVES as  quite positively 

"Why do SOME adult vegans call people that eat meat names?"

The reason SOME vegans, as well as SOME vegetarians calls people names, is a lack of maturity. However the same goes for those of us, who follows a standard diet that includes meat. I've seen plenty it coming from those whose diet like mine contains meat. Here again is a lack of maturity, especially by those who at the least claims to where they are past thirty five. 

In this section some are nothing much more than trolls. Those who has matured, has realized at least at SOME level, that not everyone can be a either a vegetarian or a vegan. However those who has failed to realize yet that not everyone is able to be a vegetarian or a vegan. Then there are some who also equally fail to realize that some of us who eats meat, have to live with diets, that are very restrictive. Yet they THINK THAT THEY KNOW factually better, what is better for us, than we do, as well as those in the medical profession, which ALSO includes medical dietitians.

However there IS NO GROUP that holds any exclusivity to name calling. Whether it's vegetarians, vegans, those of us who follows a normal omnivorous diet, if it's those who are politically to the left or right, are atheistic, theistic, or in any other area where name calling takes place. Those who stoop to name calling of ANY TYPE, and NEVER with any truly good reasoning what so ever, seriously needs to do a good bit of maturing.

Don't poke the vegetable people. They may call you names but at least they won't bite.

I think that it's VERY rare that any ADULT vegans do as you suggest. In fact, the vast majority of vegans are simply people who choose not to consume or use any animal products at all (like I choose not to consume eggs produced by battery hens). They don't even  comment on any one else's preferences.

To actually answer your question though: because there is something wrong with them - they are either simply stupid or they are mentally disturbed.

You have one answer from the sort of idiot I'm thinking of. I won't name him but he thinks YA is a “forum” where he can post one piece of ill-informed rubbish after another. It's not, it's a site where so one posts a question and other people answer it.

Which kind of names are they calling them? Like Bob or Jeff or Samantha? Maybe they just like to use a person's name when they talk to them. Personally I usually just use Sir or Ma'am. 

Because they're tired of you calling them derogatory names, teasing and taunting and insinuating that there is something wrong with them because they choose not to eat animal flesh.  

Because they’re mad that they’re slowly dying of malnutrition, but they’re too uninformed to understand it. It makes them cranky, they begin name calling, then they shrivel away and die and go to the underworld where they’re used as a human green bean side dish with Satan’s steak dinner.

That's an unfortunate side effect of being an idiot. Thankfully not all vegans behave that badly. Some people get all wound up in their underwear over their causes and take things too far. People are entitled to whatever they feel is right for themselves, what some of these dodo's need to learn is that they do NOT have the right to force their choices down others throats.

Eating natural protein allows us to be healthier and live longer.  I eat meat maybe once a week to get vitamin b12.

Name calling is only for conservatives.