(USER IS IZUKU) You and Katsuki have been friends since childhood & u have always called him Kacchan & I mean ALWAYS. You both got into UA together. It's Saturday in the UA dorms & u decided to see how Katsuki would react to u calling him by his actual name instead of Kacchan like normal.

You walked past the couch that Bakugou is sat on in the main room

You/Izuku: "Hey, Bakugou."

Bakugou: "Hey, nerd."

He's focused on his phone and hasn't realised that you didn't call him Kacchan... yet...