Is this Workplace Hostility?

I feel that my workplace is hostile with a gang mentality. I've seen this particular group torment various employees until they lashed back and were fired as the victims looked like the aggressors. Here's yesterday's scenario: I was at a work function and got a piece of pastry. Two guys walked behind me on their way out the door. I said hello to one of them and I heard the other make loud imitations of a pig. I turned around and looked at the guy who did it, and I heard him say to the other one as he looked at me, "She turned around". I was quite angry and by the way, he's fat and I'm thin. Do you think that this constitutes harrassment?