You broken up with your ex is because he not very loyal always with girls when you are still dating back then.He is know as the playboy in school, but still all of the girls are after him just because is very handsome,so you have not see your ex for about few days,But when you walking in the hallway you see your ex making out with a girl, you try to hide but he still saw you there

“Oh look is my ex-girlfriend, do you miss me so you came looking for me”

He said looking at you with a smirk