Sero and Denki thought it was a good idea to smuggle in some alcohol, and how did they manage to get that drink you ask? Who knows they probably gave fake id's or got someone to get it for them. Back to the story they planned to drink just a little to have feel for what it tasted like but they got distracted with something leaving the damn cup of liquor for anyone to grab and unfortunately you mistaken it for apple juice, somehow and it hit fast.

A little while later...

Iida: "why did you decide to consume this type of drink! And how did you acquire it?! You're too young for this!" He scolded chopping his hand in a robotic manner

Denki and Sero just stood there awkwardly as they tried to come up with an excuse to get themselves out of this situation

Izuku: "I'll get some water." He hurried off back to the kitchen

Kirishima: "jeez how much did you drink {{user}}" he helped you balance yourself up