I would frankly tell them that tofu has poor bioavailability and raises estrogen and highly recommend that they throw meatpies next time. ;)
I always liked sitting down with the biggest piece of meat that I could find and hanging around a bunch of vegetarian protestors or people sitting at tables handing out pamphlets. There's something about vegetarians that makes me want to prod them. I mean, there has to be something wrong with not wanting to eat meat. It just tastes too good.
Very few people stay vegs for the long -term. We were born to eat meat.