I remember one incident, but it was actually quite funny in the end.
I was with a friend who wanted to go to McDonald's. I wasn't buying anything to eat, but she needed the loo so I said I'd stand in line for her to save her place. So she went off, this group of lads came in, and barged right past me int the queue! So me, not being the shy, retiring type back then, confronted them on it to which I got the reply "Well, it's not like you need food anyway, you fat cow"!
I went absolutely mental, started shouting at them, told them I'd changed my mind and didn't want to be around such company and stormed off to find my mate in the loo. I told her all about it, then she stormed out and started having a go at them herself *lol* Then she dragged me outside and we started going over to one of the shops nearby - when I asked why, she said that she'd recognised the uniform of the guy who insulted me and was going to complain XD
So we stormed over there, demanded to speak to the manager and he was horrified - the lad came in while we were there and the manager made him apologise to us and gave him a verbal warning. We said thank you and then left.
My poor friend never did get her burger though *lol*