Ged-oudda-here! - Is the Wall Street Journal trending younger and trying to be hipper? Or does it just seem that way, when they publish articles like this one, explaining the origins of the "sassy" and ironic use of "Shut up!" I suppose they feel the need to cover these things when 32-year-old white (straight?) male chiefs of staff to California assemblymen start using such slang, as described in the lead-in. According to the paper,

Shut up! is the latest example of a linguistic phenomenon called amelioration, whereby a word or phrase loses its negative associations over time. A classic example is "nice," which meant "stupid" up through the 13th century. Recent flip-flops include "bad" (as in good) and "dope" (as in great). "Words that were once considered rude are now included in regular conversation, but in a context that lets you know it's not impolite," says Connie Eble, professor of English at the University of North Carolina at Chapel Hill and the author of "Slang and Sociability: In-Group Language Among College Students." "They become so generalized that the shock value wears off." Words with rich semantic connotations "typically have the possibility to mean their opposite when used in an ironic or joking context," adds Bert Vaux, an associate professor of linguistics at Harvard University.

And there you have it. Dawg.