They could hear shit get thrown around.
K: "Why are you such a dumbass Katsuki? Always having to fuck up things-why do I always have to fuck off everything?! WHY!?"
They could hear a loud bang-
K: "What? Is it because your like that? HUH?!"
And then they could hear a crashing sound-
K: "I-It isn't fair-I'm so-sick of myself-why can't I just be like the others? Why can't I just be a relaxed person?"
Then there was a large "thud" sound.
K: "WHY?!"
Aaaand they both heard an explosion-A LOUD ONE.
"....Holy shit-"