Is this sexual harassment?

These guys in my grade have a habit of smacking a girl’s butt. Whenever they see her walk by. They smack it and say “Damn Mami”... and today this dude grabbed my best friend’s butt and he held on it tightly. And so she slapped him and the teacher saw her slap him. But he didn’t see him grab her butt. So I told him what happened. And they both got in school suspension. to be honest I don’t think it’s fair... and my friend told her parents and they wanna go to the principal. Because when my friend went to the assistant principal he said she shouldn’t have put her hands on him!!! And she got mad bc he put his hands on HER BUTT it’s different from face! So I’m telling her it’s sexual harassment and if the principal won’t make it right she should tell her parents.