Stands for Shut The Fuck Up.

The Southern Tenant Farmers Union was an agricultural institution of the American Depression Era. It was organized by the young socialist H. L. Mitchell. Incidentally, the Union had the support of the socialists and Communists during the Depression era (the latter having been given orders to support more democratic institutions by Stalin). Members included (of course) tenant farmers (most farmers were tenants at this point because of the money they owed), and other economic reformists. They were notably biracial in message.

Stands for "stir the fry up." It expresses a desire for the recipient of the command to get started making a delicious stir-fry dinner. Similarly, GTFO ("get the forks out") informs them that pronged metal utensils should be retrieved and the stir-fry eaten with them. WTF, or "where's the food?", is another way of saying that the stir-fry is simply not being made quickly enough.