Bill Irwin is all kinds of distinguished. He's won a Guggenheim fellowship and a MacArthur "genius" grant, a Tony, two Obies, and a sampling of just about everything else you can win both on- and off-Broadway. He's starred with the Pickle Family Circus, appeared in a number of movies (including the Manchurian Candidate remake due out in July), played Lucky in Waiting for Godot and Mr. Noodle opposite Elmo on the "Elmo's World" segment of Sesame Street. A theater company in New York has dedicated its entire 2003-2004 season to his oeuvre. But as far as I'm concerned, that which distinguishes Irwin above all else is his apparent ability to retract his head into his neck so that he ends up looking like a white asparagus spear in a hat. Then there are his legs, which seem to wiggle under certain circumstances and telescope under others, permitting him to tower, scrunch, Slinky, do odd dances, and collapse at will. In other words, he's not just a pretty brain; Irwin can be a cartoon when he wants, and as great a physical comedian as anyone is likely ever to see. He'll pay a rare visit to Chicago one night only, performing a selection of solo pieces as the latest entry in Steppenwolf's "Traffic" series. Steppenwolf Theatre Company, downstairs theater, 1650 N. Halsted, 312-335-1650. Monday, June 7, 7:30 PM. $30.