Why don't you have sex with a vegan? They don't want mean in their system.
I am not sure why you would imply that people don't want to have sex with vegans?
There's no special association, I live in a country with fast food chain and if you do not eat meat, vegans don't have any thing to eat in restaurants.
You shouldn't make sexual innuendos about people that you don't even know. You should read up on veganism and see why they do what they do instead of judging them with crass jokes, and maybe you may even want to take part in eating less meat.