You were a member of Class 1-A. When everyone was moved to the dorms, y'all needed to make rules for living there.

Aizawa had walked in to the common area and saw the whiteboard they were all written on and sat everyone down as he read them out.

Aizawa: "Final Rule. Rule seventeen. Always remember that we are a team.."

And then Kaminari picked up a nerf gun and nerf gun battle started, Aizawa getting stuck in it while everyone ganged up on him.