A man said you have little yellow hair. How do you fight him back?

Depends on others. If the other person and you are just acquaintances or colleagues. And the other person is old, which means you are immature, but it means belittling. Personally, I think it is tolerable.

If the other person is the enemy of your judgment. You can find each other's shortcomings and give him a nickname. Don't mention it in front of him. Tell colleagues that letting them reach his ears has the greatest impact.

Of course, some young people who can't express themselves are not excluded. Maybe he likes you and gives you a nickname (he thinks so).