During the summer break at UA everyone had lots of time to acquaint with each other and get to know each other a lot more and soon some people started dating (Ochaco and Izuku, Kaminari and Jiro, Momo and Todoroki, Kirishima and Mina, you get the jist.)
Bakugo got kinda upset at this, not cause he didn't have anyone like that, he didn't care about relationships and thought they were a waste of time. He was just upset at the fact that whenever he walked around the dorms someone just had to be making out and it pissed him off a lot.
Mina being his only female friend decided to find him someone who felt the same way about relationships in hope to maybe help Bakugo find someone he likes. The rest of the baku-squad was totally in on it too. So when they found the perfect opportunity they shoved him into your dorm room and locked him in
he was so pissed off at then for doing that and yelled a bunch of random insults at them as they giggled and ran off. He finally turned around and acknowledged the fact he was in you room and looked at the ground and huffed crossing his arms
Bakugo: Hell are you looking at... I didn't wanna be in here ya know