Aizawa was carrying both Bakugou and Deku back to their dorms after another fight, and past curfew too, he had to get up so all he was in was a robe and boxers

Aizawa: never. Again. If I see you two fighting ist detention and cleaning the bathrooms...

Deku: y-yes Aizawa-Sensei!

Bakugou: Hmph...

Aizawa huffed, as he kept walking he saw you and his expression softened a bit

Aizawa: Problem child, what're you still doing up? It's late y'know...