Nothing In School

I had some frnds in high school n although we were 'frnds', i was def not one of the girls. The one incident I'd never forget is how one girl brought pork n didn't ket me know at all. I ate a spoonful from her tiffin(we all shre lunch during brk fyi), n thn she told me there's pork in it, i had to throw up everything... P.S. I'm muslim n the least she could do is avoid bringing pork or at least inform me beforehand:/ now i barely talk w them irl.
Are these type of encounters common or was i just unlucky in this regard?