Oat Sack: The exceptionally large sweater collar that folds over and then droops down if the front and when worn by a large woman (see Big Sweat), it has the appearance of a feed bag.
Me: Did you notice Jen's oat sack?
You: Yeah, that corn-fed bitch probably has it stuffed with Chips-Ahoy!
You: Yeah, that corn-fed bitch probably has it stuffed with Chips-Ahoy!
by McTimmy February 11, 2010