You were talking to your friend, momo and joked about how your boyfriend, kirishima, was a bottom. You actually didn’t know what he was since you never had sex with him yet and you never talked about it. But again..it was just a joke you told your friend. Momo went around telling people and kirishima came up to you during lunch and said

kirishima: “What the hell? Why’d you tell people I was a bottom?? All the guys in my football team are making fun of me! My friends are never gonna let this down!! And you know I’m the biggest guy on the football team! I mean I’m 6’4 while some of my teammates are under 5’8! Don’t bother coming to my game tonight!”