Senate Minority Leader Robert J. Dole (R-Kan.) knows, of course, that humor can be a political hand grenade, likely to explode in your own face. But he can't help himself, which is why California voters are hearing an old Dole comedy routine exploited by Democratic gubernatorial nominee Dianne Feinstein to mock Dole's colleague and friend, Republican gubernatorial nominee Sen. Pete Wilson.

A new Feinstein television ad replays a tape of Dole describing the day in 1985 when Wilson was wheeled into the Senate shortly after an emergency appendectomy to vote for cuts in Social Security and Medicare. "He was under heavy sedation," says Dole, clearly entertaining an audience with the story. "I said 'vote yes,' he voted yes and we rolled him out again. . . . He does better under sedation."

The Feinstein announcer warns: "Imagine what {Democratic Assembly Speaker} Willie Brown and the legislature would do to him in Sacramento."

Wilson, unamused, immediately called it "the ugliest and most mean-spirited commercial of 1990" and demanded that Feinstein take it off the air. He said it was a retread of a 1988 commercial used against him in his Senate reelection race, and was withdrawn then when "the media howled in protest." Dole wrote Feinstein to call the ad "character assassination." His remarks were "a harmless joke," he said, but as Dole knows, in politics that is often an oxymoron.