The right wing seems to take such delight in carelessly throwing around this term, that I have to share this from Al Franken's "Lies and the Lying Liars Who Tell them".
"In her book 'A Distant Mirror: The Calamitous Fourteenth Century', Barbara Tuchman writes about a peasant revolt in 1358 that began in the village of St. Leu and spread throughout the Oise Valley. At one estate, the serfs sacked the manor house, killed the knight, and roasted him on a spit in front of his wife and kids. Then, after 10 or 12 peasants violated the lady, with the children still watching, they forced her to eat the roasted flesh of her husband and then killed her. *That* is class warfare. Arguing over the optimum marginal tax rate for the top 1% is not."