Hey, what'cha got there?

It doesn't happen often but on occasion I am forced to each lunch at my desk. For some reason on those days someone always comes into my cubicle and asks "Hey, what's for lunch?" or "Hey, what'cha got there?" That's when I ask them "Why, do you want to trade?" Some people usually laugh and others aren't sure if I am joking or being serious. It is neither actually. I am just annoyed. Why is it that people feel inclined to interrupt my lunch by making stupid comments and asking questions, which 99.99% of the time could wait the twenty minutes until I finish eating?
If you see me eating, do me and yourself a favor and leave me alone. Because if you interrupt me, the level of service you receive will be that of a hungry and pissed off IT guy. It won't matter what you ask, my answer will basically be NO and not because I can't do it, because at that moment I hate you guts.

You have been warned.