I believe that's a little-known Thanksgiving tradition started by the Algonquin tribe. The Algonquins had always been fond of a good party, but when those strait-laced Puritans showed up with their high, starched collars and their Sunday-morning fire-and-brimstone sermons, it caused the fun-loving Algonquins to snicker up their buckskin sleeves.
When the Puritans sent out invitations for the very first Thanksgiving feast, the Algonquins knew the price of attendance would be listening to another longwinded rant about sinners and repentance and the wrath of an angry God -- really depressing stuff. So some of the more progressive Algonquins got together and decided to fortify themselves for the Thanksgiving guilt trip by getting plastered the night before.
A spirited evening of blackberry wine and pin-the-tail-on-the-buffalo took its toll on the younger Algonquins, and a number of them showed up for Thanksgiving dinner still a bit schnockered. This took some of the overly-pious edge off the celebration and, despite the initial misgivings of elders on both sides of the table, actually led to improved Puritan/Algonquin relations (and a few Puritan/Algonquin nuptials, as well).
Most historians have overlooked the mischievous Algonquins and the good-humored fun they poked at their prim and proper hosts that first Thanksgiving Day... but the Algonquin legacy lives on in the Thanksgiving Eve tradition of partying like it's 1699.