For somebody, yesterday was a big joke. For the Washington Capitals, it was another of those days that try men's souls.

After spending hours assuring people that Robert Picard had not really been traded to Montreal, Capitals Geheral Manager Mrs. Max McNab heard some news that was true. Winger Tim Coulis, the team's second selection in the first round of the amateur draft, has a broken left wrist and will undergo surgery at Arlington Hospital Monday.

"I hurt the wrist in that first (rookie) game with the Islanders (Sept. 23)," Coulis said. "I didn't tell anybody for a while, but the pain was so bad that I finally said something after the game in Quebec (Sept. 30). It hurts anytime I try to move it - up, down, anywhere."

The initial diagnosis was a jammed wrist, but it now develops that the same bone is broken that took so long to heal in Rick Green's right wrist in 1977. So Coulis will join the club's other first-round selection, Ryan Walter, in civilian clothes for the rest of October, at least. Walter underwent knee surgery Sept. 13.

"Anytime we think we've gotten out from under that dark cloud, it comes right back," McNab said.

A prankster called the Montreal newspapers late Thursday night, posing an official of the Montreal Canadiens, and reported that the club had obtained Picard and Washington's No. 1 draft choice in 1980 for center Pierre Larouche, defenseman Brian Engblom and goalie Bunny Larocque.

"My mon called at 8 o'clock this morning and asked when I was coming in," Picard said. "It was on the front page of the Montreal papers. I've been getting phone calls from everywhere."

Rumors of a deal for Picard began surfacing two weeks ago, when Montreal defenseman Bill Nyrop suddenly retired. They escalated when Engblom suffered a broken jaw. On Wednesday, Picard went to Washington General Manager Max McNab, asking for a definitive word. He was told he would not be traded, but he still wondered and said he will not be able to relax until after Monday's waiver draft.

The effect on Picard's emotions is compounded by his lifelong ambition: to play for the Canadiens.

"I'm not taking anything away from the Washington Capitals, but the big Montreal Canadiens . . . I'm only 21, it's a little hard to forget I come from there," Picard said. "If I was 50 years old and ready to quit, maybe I'd know there was nothing to it. But I wish one day I'll be with the Canadiens. I'd love to play for them. It's my hometown. Those are the people who taughte me hockey.

"But Washington is treating me outstanding. My heart is with the Washington Capitals now. It's just that all this mixes me up. It would mix anybody up."