"Where's Johnson?"

In researching yesterday's obituary of arts critic Clive Barnes, I found this fun excerpt from Time magazine:

A few years ago during the presidency of L.B.J., Dan Sullivan, then second-stringer to Clive Barnes on the New York Times, was sent to Washington, D.C., to cover a play. Stewart Udall, then Secretary of the Interior, passed Sullivan on the aisle, and asked the perennial question, "Where's Barnes?" Retorted Sullivan, in what has become the classic second-stringer's revenge, "Where's Johnson?"