So *not* true.
I just came back from a potluck with maybe 20-30 vegans there. They're actually all pretty normal and intelligent people. None of them fit this silly stereotype.
I don't announce myself unless necessary. I never harass carnivores, it's always the other way around, and their responses are predictably silly (and easy to deflate).
But I guess all black people are thieves, all gay people are promiscuous, all women are s**ts, and all males are child molesters, right?
The meme at left is an example of what'd be closer to semi-intelligent humor on the subject. Remakes of this silliness every week are really not.