I have known several vegetarians who use their eating patterns as a form of spiritual one-upmanship. They are purer than anyone because they never even walked into a restaurant where meat was prepared. Or they loudly announce when invited to dinner, “I’m a vegetarian” and remind the host periodically until the actual event. Then they grill the host to make sure that no animal products were used in the preparation of the meal. They may even present the host with a list of what they will and will not eat.
Now we are mixing moral superiority with entitlement and that is not a pleasant sight. Militant and moralistic vegetarianism is not a non-violent position towards living creatures if you are hurting other’s feelings in the process. Eating a meal lovingly prepared by someone who unselfishly wanted to please you may be the most nonviolent thing you can do in this situation, even if it contains some animal products.