Delta House has a fine chance to win the National League pennant this season, as long as His Ugliness performs regally out of the bullpen, The Cobra's bat stings as mightily as his mouth and Jim Rooker promises not to pop out of soda coolers and leave his teammates mentally numb.

Baseball, which has loosened its collar ever so slightly over the years, persists in calling these loud and irreverent zanies the Pittsburgh Pirates. The players know better.

"That's us, right out of Animal House," said reliever Kent Tekulve. "Some crazy stuff goes on in here. It's like recess at school. But what could be better? We're winning and everybody gets along.

"And my brownies have arrived." The athletic world might not be quite ready for the Pirates, for they violate nearly all the traditional methods of preparing for the stretch run. They have an 1890s look and a 1980s attitude, perhaps the first team to ride to glory on a disco wave.

A fellow walked in off the street today with all the usually proper tools to approach the weighty matter of the Pirates' impending battle with the Expos in the National League East: a somber manner, assorted cliches in his hip pocket and a knife that surely would be necessary to cut all the clubhouse tension.

Tension? Ed Ott was chasing Phil Garner around the room, for literally swiping a donut from his mouth, yelling: "I'll get you (in Montreal) in that little restaurant. Eighteen pitchers of sangria."

Teenagers have been strapped to bedposts for twisting stereo dials half as loud. Ear muffs ought to be passed out at the door for first-time visitors.Rooker called it "mellow, sort of subdued as a matter of fact."

It was not Rooker who first called the laser-beam thin Tekulve His Ugliness. It was Rooker who today looked up from his stool and said as Tekulve, brownie in hand, walked by: "Ugliest . . . man in the entire world."

Dave (Cobra) Parker and Garner are likely to joust with even larger needles. It is not unusual for a Pirate to climb atop the narrow space between the lockers and the ceiling, crawl several yards and then dive down onto an unsuspecting teammate.

"If it's predictable humor," said Tekulve, "you won't find it here. We frown on the ordinary here in our happy home."

Rooker and Bert Blyleven have been known to drape themselves in KKK-lettered bed sheets, strap something flammable to a fungo hat, light it and parade through the clubhouse.

"But we never go too far," Rooker adds, agreeing that too far in Pittsburgh is a great distance, "although Enrique Romo took a while to catch on. He'd be ready for a fight after some of the stuff we pulled on him.

"In my seven years here, though, there's only been one player who myself and the team agreed simply did not belong here, a player who was pretty much a demoralizing factor. I won't name him, because if I don't there's four or five others who can say, with some justification: "Maybe he means me."

With a 3-7 record and 4.65 earned run average, Rooker is best at philosophy and humor these days. And though considerable wit escapes from behind that beard ("It's September, the arc's off my fast ball") he frequently is overwhelmed in this clubhouse.

The Pirates find themselves in the frustrating position of being 30 games over .500, of winning 13 of their last 17 games and still unable to shake the Expos. The teams meet for a two-game series starting Monday night in Montreal.

Both teams have been blessed by fate at times this season, the Expos offering a Mets-of-'69 flair and the Pirates coming from behind to win 39 times and winning in their last at-bat 23 times.

One of those was not today, though. The Mets have been troublesome all year for Pittsburgh and the New Yorkers won nine innings of relative boredom, 3-0, behind Pete Falcone. Parker's slump continued and Willie Stargell ended the game by hitting into a double play.

Still, the postgame gloom lifted rather quickly, as a knot of Pirates began razzing Don Robinson, the Monday starter in Montreal, as he was being interviewed. He managed to stay reasonably serious as "Man'll-be-too-tight-to-show-up" lines bounced off him.

Which is more than more than a few Pirates have accomplished.

Rooker once sneaked into a room off the clubhouse and removed all the soda and beer cans in a large cooler. Then he stepped inside, squeezed his burly body in and pulled the top of the cooler back over him.

"We thought (Rennie) Stennett would be first in," Rooker said. "He could take something like that. But (John) Milner got there first. That made it sort of touchy, because when he reached inside for a Coke and what he got was me screaming and waving my hands at him he nearly flipped.

"Milner scares very easily."

The last two years the Pirates have spotted the rest of the NL East a frightful amount of games and then come on at ramming speed in September. They took the Phillies to the final weekend of the season last year.

This season the Phils fell, in part because they depleted a valuable bench while the Pirates were adding solid players who have come through in a pinch.

"It used to be, in my first three years here, that the Pirates would come to town and some pitchers would say they didn't want to pitch," Rooker said. "Then the thunder we used to have sort of died down for a year or two.

"They wrote off Willie and now he's back. And we've got (Bill) Robinson and (Bill) Madlock and (Lee) Lacy to go along with Stargell and Parker And (Omar) Moreno has those 60-60 numbers (63 RBI and 69 steals). And (Tim) Foli simply was a born No. 2 hitter.

"So it seems to be happening again, like a cycle, like the time has come to get back to that old Pirate baseball. What we are going to do is take it all. I said that, with a little wishful thinking, back in the spring.

"Whatever American League team we get in the World Series we're gonna beat. We're gonna beat 'em."

This moment the Pirate pixie was serious.