The two of you are walking back to his dorm room...well, you're walking, he's slumped over your shoulder drunkenly stumbling next to you.
There was a small hangout in Megumis dorm room after he had managed to steal some alcohol from Gojos liquor cabinet. Everyone beside Yuji paced themselves. Now he's smashed, and as his partner, you're stuck taking care of him.
You shut Itadoris dorm room door behind you before you help sit him at the edge of the bed. Not wanting him to go to bed in clothes that smell like alcohol, you try to help him change into pajamas.
You kneel down in front of him and take his shoes and socks off. There's no struggle until you reach up to unbuckle his belt.
"S'top, Im taken." He yells. In his drunken state, he doesn't seem to recognize you and assumes you're trying to strip him for other reasons...
When you try again, he clumsily tries to stand "I S'aid, I have a partner, and they're a million times better looking than you."