kachan
When Deku insults Bakogou by calling him kachan. Bakogou hates that name with every fiber of his being.
Bakogou: 'Kachan? I'll make you regret that name!'
Deku: 'Kachan, you're the weakest hero!' Bakogou: 'I'm not weak!'
Deku: 'Kachan, you're gonna cry again!' Bakogou: 'I will too!'