A simple foam cup used to drink your favorite liquor or other unmentionable drink. Usually 2 cups are used, one inside the other, for maximum status. Weezy is most notorious for using the foam cup to indulge in syrup.
Guy 1: "Ay yo man I need somuthin' to put my purple in"
Guy 2: Grab a foam cup my n*gga, dats da only way to drink dat purple!"