Ok, genuine question, and I've been around here long enough to know this is probably going to descend into a bunfight but meh 
Seriously. Why?! I've only recently noticed it since doing Veganuary and mainly carrying it on now even though it's finished. Up until then, I eat everything - fish,meat, cheese.....but at the same time eating lots of vegan and vegetarian food too as DH is a long time vegetarian.
(Who's gone vegan after completing Veganuary.)
Been out for dinner today.
"Surely you can have a little bit?!" (Erm, no
)
We've also had "but it's not healthy!" (that all depends on how you do it,surely? I know I was eating a lot healthier during Veganuary as I was conscious about what I was eating and not just mindlessly shovelling stuff in - even though I love mindlessly shoving stuff in 
Or you'll get a bacon sandwich shoved in your face. "You want this bacon, don't you? Don't you?"
Erm,no not really. 
I don't give a shit whether people eat meat, why are they so bothered that I'm vegan for a while?!
Must be exhausting to be a proper one!
not including the militant ones that tell you meat is murder as they can just go away and practise the saying each to their own...