Who are you calling fat?

At some point in your life I am sure you have been called a name. These names usually changes from things like "butthead" to "bitch" but some seem to stick around. How about "fat". The other day I was called that by an obese girl while I was eating an apple. No lie.
I really did not know what to do. Morals told me not to say anything because after all she may be feeling bad about herself and I would never want to seriously harm anyone. Instinct, on the other hand, told me to "call that bitch out" as one of my friends so kindly put it. I ended up just looking blankly at her and blinking a few times, luckily I was saved by the bell and was able to escape before I did something I would later regret. It really was the strangest thing.
This is the whole scenario from start to finish:
Some background information about myself- I am a black hole and am ALWAYS hungry, I am also 5'10" and 145lbs.
Back to the story; I was sitting in my first class of the day thinking about my two favorite things: food and sleeping. I have food with me at all times because when I get hungry I don't get the typical crabby, I get shaky and weak to the point that I can't stand (I think I may be hypoglycemic) so I decided to problem solve and eat an apple discretely since I sit in the back corner of the class and no one knows who I am and I don't know who they are. I pull out a delicious crisp apple that I had purchased the day before and begin my feast- All the while careful not to draw attention to myself I keep my head down and only eat when someone is talking. Suddenly I hear, "Damn, you fat as hell, always eating and shit- you don't need that." At first I thought it was my teacher speaking and I was surprised to hear her talk in such a casual style but I look up to see the planet of a person looking at me with eyes that would make the devil question himself. Now the whole class is looking at me with food in my mouth. Can you say awkward? A few tense minutes later the bell rang and I sprinted out of there.


This is on a different topic but slightly related; it's about people consuming things. I was not in the class when this happened but a few days ago someone came up to me and asked if I had heard about what happened in one of the classes. I said no but was immediately interested because of the excitement in her voice. The school policy is that you can not leave the classroom unless it is an emergency, so no bathroom, no water fountain, most of the time not nurse either. One of the teachers has a pitcher of water and some plastic cups if a student is thirsty. In my opinion that is very smart, he abides to the school rules while understanding that teenagers do in fact need water from time to time. A senior (because this teacher only teaches senior classes) put rubbing alcohol in the pitcher so when a student in that class asked for some water they drank that instead. This student became very ill and needed to go home. I suppose I am just not hip and with it since that does not seem funny to me at all. All I can say is that I feel so bad for this teacher. He is way overqualified to teach high school, he is always happy, always nice, believes what his students say, and yet people are constantly taking advantage of that.
I have to remind myself that this is public school.