Sonny Jurgensen often jokes that if present squishy-soft NFL rules had been in force a generation ago, he'd have had 300-yard halves. Well, a guy whose name sounds as though he ought to be a shoe heir, Bill Kenney, passed for 275 yards the first 30 minutes at RFK Stadium yesterday. And the quarterback who wants a best-in-the-game salary had his cleats caught in his mouth.

Joe Theismann will be the first to admit he heard the boos spill over him, like a pleasant shower suddenly gone icy.

Truth be known, he was leading 'em.

"Didn't throw worth a damn the first half," he admitted.

Theismann missed an acres-open Joe Washington, which both later said was excusable; he also threw low toward a Smurf, which wasn't. That's when Theismann got cross with himself. His first touchdown pass was a too-hard, too-high peg that flew off Nick Giaquinto's fingers at about the five and into Don Warren's arms at the goal line.

Or 1-6-3 if you're scoring.

Theismann's ugliness was all the more vivid for two reasons: he'd been close to flawless for so long and had come very close to demanding that his $1.4 million contract be reworked slightly more than a week ago. Familiar to the fickle faithful was Theismann's reply when asked about his leverage, should the Redskins choose to call his bluff before next season:

"They won't have a quarterback."

They didn't have one the first 40-some minutes yesterday against Kansas City. One half expected to see owner Jack Kent Cooke yell down from his box: "Joseph, we're gonna work in one of those escalator clauses; you pay me $50,000 when you're this bad."

If nobody else could quite remember when Theismann was so humbled, Theismann could.

"The worst since (a four-interception half) against the Giants here last year," he said.

There was a reason.

"I've been fighting an infection most of the week, and I just felt blah the first half," he said. "My body figured if it's Sunday it ought to be able to take the day off. Talked myself out of it later. Thank God they make these things 60 minutes."

Fortunately for Theismann, the defense was blah only till the Chiefs got close to the end zone. Kenney and a half-dozen or more receivers were awesome-looking 90 or so yards down the field; the final few they were anemic. That's because they run less effectively than a Republican in District elections, and the Redskins could concentrate almost soley on Kenney.

Mike Nelms ran much farther, 55 yards to 33, on seven punt returns than Kansas City backs did on 17 carries.

Washington scored all its points in the second half; it won the game in the first, when the defense kept the Chiefs to 12 points instead of 28. Theismann owes the defense dinner for saving him, with extra dessert for Darrell Green, Dave Butz and a few others who had their hands either on Kenney or his passes when that meant the difference between a field goal or a touchdown.

"Ain't no rookie no more," Otis Wonsley, yelled toward first-year cornerback Green, whose third-quarter interception set up the Redskins' first touchdown. Wonsley then volunteered an overview of the afternoon: "It's always nice to see what a team's made of."

This one yesterday was made of everything that fetched Super Bowl rings last season, with one large exception. Joe Washington now hops off the bench and deep into the secondary whenever John Riggins needs a rest. Washington would like to play much more, and plans to. He also knows better than to fuss about a system successful in 17 of the last 19 games.

And Theismann was bright enough to allow Riggins and his Hogs to wallow about until his blahs passed, and he could pass. Because so many large Chiefs were in his face, Theismann was unable to see Washington unconscionably open early in the second quarter for a near-certain touchdown. Neither could Washington see Theismann.

"Happens sometimes," Washington shrugged.

Theismann grabbed the second gift touchdown. For about two years, the Redskins have been setting teams up for such a play. Time after time on short yardage, they have pounded Riggins between the tackles. Now, Theismann faked to Riggins and looked upfield for what he hoped would be a reasonably open Clint Didier.

What he didn't see, nary a Chief defender, caused a gulp.

"Throwing to somebody that open is the most difficult pass in football," Theismann said. "If I'd blown that one, I'd have had to leave through a tunnel."

He left through the front door, with his head not quite as high as usual. It was a tough day that ended pleasantly. Everyone helped cover for him, and he was more than willing to let them. That timeout just before the first touchdown was not Theismann's idea but a Hog's.

"I'd got hit on the knee a few plays earlier, and it was sore," left guard Russ Grimm said. "Also, I was a little winded. I thought it was a good idea if me and everybody could catch their breath."

And on third and goal from the two, the Hogs set a trap that took the breath from the Chiefs. Center Jeff Bostic took his man right; guard Mark May went behind Bostic and shoved his man left; Grimm nailed a linebacker. The next time anyone touched Riggins was to pat his shoulder pads in the end zone for his 36th Redskin touchdown.

"Clean," Grimm called it.

Obscene, the Chiefs thought.