SSS, I know 'toughening up' sounds awful, but they do all need to learn that there's always some silly child who'll have some silly thing to say, and that they should just let it wash over them.
Dd1 acquired glasses in Reception, and then added an eyepatch when she was in Y1. She came home a couple of weeks after the start of term, saying, "Oh, XXX and YYY and the big girls in Y 3, they keep calling me four-eyes". I suppressed my immediate urge to go round and Sort Them Out, and asked her what she'd said to them. To which dd1 replied, "I said, 'Well, I told them, you're two years older than me, you should know better'."
Ds is currently having a bit of an issue with a boy in his class who is nearly a year older, sees himself as the class alpha male and likes to throw his weight around. Ds is pretty much the only boy who really challenges this other kid, so takes the brunt of his windups (verbal, rather than physical). It does still get to him, but has been greatly improved by teaching him new ways of looking at it, eg. he's a silly boy, he's jealous of you, blah blah.
Maybe you could try something similar with your dd? Eg saying that some children are a bit immature, and haven't yet learnt to solve arguments sensibly, or to behave nicely. Somebody posted this link to an antibullying website on my thread about ds's problems , and I do like the approach it suggests. In the end, you can't do much about the other children's behaviour, but you can try to change the effect it has on her.