Randi Rhodes, the leftist talk-radio host who found herself in hot water yesterday for airing a skit that warned President Bush with gunfire, has joked about assassinating the commander in chief before. Last May, Rhodes, who hosts a show on the struggling Air America network, imitated the sound of gunfire while saying somebody ought to take the president fishing and then shoot him. On May 12, New York Daily News columnist Michael Goodwin wrote a piece criticizing Air America, saying he had listened to the liberal radio network one day for 10 hours. "The queen of venom, Randi Rhodes, followed...