Sexual harassment/assault should be stopped!

Yesterday, one of my female classmate told me that our male classmates were talking about me. At first I didnt bother since its not my business anyways, then later I was sitting right next to my male friend then suddenly his friends circled around us and they started teasing him about him staring at something yet he kept on denying and I didn't really mind it at all cause I thought maybe its just one of their own inside jokes, then a few minutes later one of my female friend came up to me and told me that the male classmate I have been friends with have been talking about how big my chest are. I really cant believe that he would do something like that. And about my male clssmates teasing my male friend...... He was actually staring at my chest and they made sexual jokes about it.