Its pre-gaming not pre-drinking. It was meant to mean drinking before going to the football game that had expensive ass drinks but it was applied to anytime you were going out when you had to buy drinks
In subreddit r/todayilearned
In a post titled:
TIL: 'Let's Get It Started' by the Black Eyed Peas was originally titled 'Lets Get Retarded' with lyrics to match