Mate crime is when someone pretends to be a friend or a mate to another person, but actually hurts or takes advantage of them. It's like when a bully pretends to be nice to someone so they can get something they want, but then they start being mean to them. This happens a lot to people who might be vulnerable, like the elderly or those with disabilities, who might not realize that someone is taking advantage of them. It's important to make sure you only be friends with people who are really nice and not just pretending to be nice. And if someone is treating you badly, you should tell a trusted adult or friend so they can help you stay safe.