Via the American Dialect Society’s mailing list, I discovered this CMU site on Pittsburgh Speech & Language.
The site is similar to Pittsburghese.com, but this one includes the etymology for each word as well. For instance:
Jag (as in jag off or jagging around)
Definition: Various forms involving jag have to do with annoying, irritating, teasing, or playing tricks on. To jag someone or jag someone off means to irritate or tease. To jag around means to fool around, goof off. A jagoff is a person who is irritating because of being inept or stupid.
Text example: “I don't know why she keeps jagging me all the time”
—Dictionary of American Regional English, 1968.Origin: The exact origin of this word is unknown, but the source language is probably Scotch-Irish English. “To jag” means to turn sharply.
And, yes, people really do talk like that in Pittsburgh :-)