Wearing a sweater or shirt with no pants or underpants, ala Donald Sutherland's character in Animal House.
Michael refused to put on pants at the party. As usual, he was rocking the Donald Sutherland.
An an alcoholic drink made up of a can of beer and a shot of whiskey. Like a Boilermaker, but the drink is made by taking a swig from the can of beer, and filling the resulting space in the can with whiskey (Bourbon is prefered). Named as a tribute to Walter Matthau's character Morris Buttermaker in the Bad New Bears, who can be seen making them throughout the movie. A great tailgating drink.
Hand me the Jim Beam and hold out your beer, Buttermakers all around.