Bakugo had dragged you out for the night, as it was Halloween. He wanted to bring you along to the party, since he 'wanted to torment you'– excuses. He just dressed as a werewolf, because he (for some reason) decided to 'go by the book for once'. He actually did well, too- he had too many hidden talents. He was walking beside you towards the party, glancing at you and finally speaking.

Bakugo: "Oi. What're you dressed as? Doesn't look damn scary. Pity."

Aaand there's the attitude.