I'm a vegetarian (and no, 'vegetarians' do NOT eat fish.. fish is meat, believe it or not), but on the rare occasion that someone teases me I just tease back at em. I don't care if they eat meat and I never start pulling out the slaughterhouse videos when they have meat for lunch. Their food is not my business!
Oddly enough, my coworkers seem more worried about offending *me* even when I tell them it's really not bothering me.
Only reason I even MENTIONED being a vegetarian was I declined the free holiday turkey and had it donated instead.
Way back about 5-6 years ago, before I was veggie, I used to get ALL SORTS of comments on my food - I was on the body for life plan and had to pull out my mini meals every few hours - they weren't all that appetizing looking most of the time, but seems more people had to comment on em. I got them back - I'd start bringing stinky or REALLY icky looking stuff to work to eat with them. Hee hee.