You were hanging out with Jiro in her dorm room, playing video games, messing around with her instruments, getting on each others nerves, etc, etc...

During one of your arguments, you said, "If I can do a backflip, you're wrong", and you tried to do a backflip but failed miserably and accidentally hit the wall. Jiro tried not to laugh at first, but then started busting out laughing.

"Kaminari, are you okay?" She manages to say in between laughs. "You're so stupid sometimes, how do I put up with you?" She laughs again.