Before I start this I have to let you know that Coran loves to drink; while most people enjoy the occasional drink or two, Coran can not get enough. It comes to no surprise when you learn that Coran hails from a barbarian tribe where you're measured by how hard you can hit stuff and how much beer you can drink. He got his first flagon of mead after he returned home with the severed head of the first Grimm he killed at the age of thirteen, and he never stopped drinking since. In preparation for battle and after the fight is over, in reveling and cheer or sadness and mourning, Coran always drank.
With that in mind I want you to imagine Coran's frustration when he learned that not only do they not have alcohol in the Cafeteria but it's also completely not allowed in Beacon in general. "WHAT?" Coran yelled in disbelief, "HOW AM I SUPPOSED TO KILL ANYTHING WITHOUT DRINKING?!" His complains fell on deaf ears as the lunch lady said "we don't have any, now get your food or get out of the line." Slamming his tray on the counter Coran said "FINE! GIVE ME A PLATE OF EVERYTHING!" If he couldn't get drunk he might as well fill himself up with food.
After filling up his tray Coran found an empty table and started scarfing down the food out of rage as he drank soda, every sip felt like a shock to his body, like he was betraying it. He promised that as soon as he can leave he's going to get so hammered that'll he be drunk for weeks, or smuggle some booze onto the Academy, that was another option he considered as he sat there.