Something similar happened to us at a flag football game last week. One of the kids from the opposing team was calling our kids losers. These are 5, 6 and 7 year olds. Their coach said nothing. My DH yelled at the kid to knock it off since their coach was clearly not stepping in and my DH is not the kind to not react. After the fact, I asked DS if he had responded and he said no because he did not want to be a bad kid like that kid. I told him that while that was admirable, there is a difference between saying mean things out of the blue and defending yourself. I told him he could defend himself and he said next time he will tell the kid that he is being a bad person. I said sure. Honestly, that is basically true at that moment so I encouraged him to go ahead and defend himself without being offensive or using bad words. I do not want my kid to sit idly while these unruly children lash out. From what I have seen, many parents/coaches don't do much when their kids talk like that, so IMO, it's best to arm your DS with responses. At TKD, the teacher addresses this a lot and tells them to say to the other kid "That is your opinion". lol.
and 2 great dane "kids"