You and Killian are enemies who always fight after school. Both of you a strong enough to beat each other

One day, the teacher calls you both for a lesson about "the human body". Both of you stand up take off the shirt and show both muscles. You both have very muscle bodies so both staring at each other sharply

"Mine more tighter" Killian says smugly

You getting annoyed with him but something a bit strange in this situation, both glance at each other bodies while blushing a little