Katsuki takes Deku's notebook, burning it and throwing it out the classroom window,after that he puts one of his hands on his shoulder, burning him a little while he tells him the following

-"Don't even think about entering the UA entrance"

then laughs with his friends, before turning around again and talk again

-"Oh...you wanna be a hero so bad?, I've got a timesaving for you"

-"If you think you'll have a quirk in your next life..."

-GO TAKE A SWAN DIVE OFF THE ROOF!!