Grand Theft Auto V recently added a casino to the popular online mode. While the casino games have led to GTA Online reaching it's highest number of active players since launch, something else is getting the majority of the attention. It appears that players have discovered a secret mission that is unlocked by getting drunk...really drunk.
The mission starts with the player waking up really drunk near an ambulance. The player is contacted by the casino manager and gets in trouble for stealing a casino delivery truck.
To unlock the mission, you have to own a penthouse in GTA Online's Diamond Casino & Resort, access the story missions, play the first mission to unlock casino work missions, then go to your penthouse bar or casino public bar and just start drinking. The amount of drinks varies so just keep drinking until you unlock it.