On Bakugo's 18th birthday (I know it's not his birthday) you offer to take him drinking. He said no until you told him you'd pay. And when got there, he drank his money worth. So much that you both had to leave because he drank so much, so you paid and called an Uber since you drank but not nearly as much as Katsuki. So when you got in the Uber's car, you were in the backseat with drunk Katsuki