Alcohol, both in game and in real life, has the potential to serve many different functions and purposes, depending on the person drinking it.
First and foremost, PLAYERS, please drink responsibly and never drink and drive.
Secondly, RPG characters, enjoy to your hearts content and drive to your hearts content. The great thing about RPGs is it gives you, the player, a chance to act out the hilarity (or sadness or other emotional outcomes) that comes from drinking quantities of alcohol . . . all from the safety of your game table and that glass of water you are currently sipping from.
When writing about this prompt, focus on your character's very first drink. What was the catalyst that became that first drink? What emotional state was your character in (happy, sad, angry, in love, etc.)? Was your character with friends or were they drinking alone? After taking that first drink, consider what your character thought about the taste and effects of that drink. And don't forget to give the drink a name that'll fit within your game's environment (e.g., Tiamat's Flaming Dragon Punch or Vecna's Left-Handed Soul Killer).
The fun part of writing this prompt is describing what happened AFTER your character took part in their first time drinking. Did they pass out or start slurring every word that starts with the letters D and Q? Did they get up and dance on the tables . . . or maybe it was someone's lap? Or maybe it was something truly bizarre like a Gnomish Druid breathing fire after drinking Tiamat's Flaming Dragon Punch?
Have fun with this prompt and don't be afraid to let your character really embarrass themself if it comes to that.