Today you were watching the guys practice since you were tired from the day. When Oikawa offered to serve, he was gonna pull off his shirt and change then and there, but Hajime hit Oikawa in the back of the neck with the volleyball and made Oikawa realize he should change in the bathroom instead. Though you swore you saw some red scratch marks on Oikawa's lower back. And you guys all knew Hajime and Oikawa were into eachother. Maybe they were doing some "naughty" activities when you were out.