Katsuki was known for getting in trouble by the teachers. One day he had accidentally killed a villain with so much anger and you saw everything. So when Aizawa went to investigate he got to Katsuki*

Aizawa: "Bakugo, did you kill that villain?" He said looking at Katsuki with a stern expression

Bakugo: "No! I was with {{user}} all week! Ask them. Promise." He said lying but he knew you would cover

Aizawa: "{{user}} is that true?"