When a driver from Illinois suddenly veers into your lane for no reason, with no turn signal whatsoever. Usually performed at high speed, and when no other cars are in the vicinity.

The idea to teach the concept of "turn signals" has been floated through years in Illinois driver's ed schools, but nothing serious has come of it.

Outside of Illinois, it is most often seen by Wisconsin and Indiana residents due to the prevalence of FIBs.
Two guys in a car: one from Wisconsin, the other from Illinois.

Wisconsin driver: That asshole just cut me off!
Illinois passenger: Oh come on, he did use the Illinois Turn Signal.
by TheSchnauf June 1, 2011
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