So, the problem is, you’re at school in line to buy lunch and someone decides they want to get in front of you. Here is a skit like thing to describe how you should handle the situation:
You: (in a calm, collective way) Excuse me but I was in front of you.
Ignorant Person: Well I’m hungry too!
You: (still calm) Ok, but I got here first and its going to take the same amount of time for them to serve you behind me as it would if you are in front of me. I’d appreciate if you’d move back.
Ignorant Person: I guess you’re right, sorry.
You: It’s okay, have a good lunch.
The moral of the story is if you’re calm and polite things will most likely work out better. Even if the other person is ignorant and aggravating you it’s always better to be the bigger person and stay mature.