They didn't just make a fist. They didn't just raise their arms. They weren't just having fun. This was an angry crowd, made angry by the Giants' ineptitude and the longest strike in football history. As the Redskins and Giants left the field at halftime, hundreds of fans hurled fists toward them and chanted, "Strike . . . Strike . . . Strike." You half expected the mob to burn an NFL flag and take Joe Theismann hostage.

"It sounds a little better to have 'em boo," Theismann said wryly after the undefeated Redskins beat New York, 27-17, for their third victory of this on-again, off-again National Football League season that continues, maybe, next Sunday when Washington plays its first home game of 1982, against the Eagles. "I'm wondering now what it'll be like at home."

For the first time in 64 days, the NFL went to work today. A whole lot of folks didn't care. Rather than use the tickets they bought for today's 13 league games, 115,586 people stayed home--an average of 8,891 fans so turned off they tuned out. There were 88,989 unsold seats as well, leaving stadiums at about 77 percent capacity.

After 44 straight capacity crowds at Texas Stadium, 13,439 customers ignored the Cowboys. Nearly 15,000 raked leaves, or something, in Chicago. The Giants, with 5,518 no-shows, sold game-day tickets for the first time in 16 years because 600 season-ticket holders asked for refunds.

Around the league, there were literal signs of discontent. "Personal Foul, Fans Get Clipped," a bedsheet banner said in Shea Stadium, where someone passed out leaflets asking the fans to stand "in total silence" during player introductions.

When the little clown car from the circus rolled onto the Giants Stadium field before today's game, Washington policeman Eddie Myers shouted out, "Look, here comes Ed Garvey and Jack Donlan." Those distinguished fellows did the negotiating that led to a settlement so tentative that Garvey has predicted the players will reject it in a vote this week.

"The booing here," said Dave Butz, the Redskins' defensive tackle, "came because the fans have a tremendous amount of frustration built up. It would have happened even from the greatest fans in the world, ours at RFK, because they see ballplayers making large sums of money asking for more money. And the fans have no way of releasing the aggressions built up over eight weeks."

It didn't take long for the vibrations of frustration to ring Pete Rozelle's bell. "I think it (the strike) hurts us for the balance of this year," the NFL commissioner said on CBS. "They're going to have to work hard, both the owners and the players, to get through this season and then to finish it on an up note."

"I didn't even notice the booing," said Mark Murphy, the Redskin representative to the players' union. The strike, in which Murphy campaigned for 55 percent of NFL revenue, was still on his mind when someone asked about a near-interception that fell off the safety's fingertips today.

"I was negotiating for 55 percent of the ball," Murphy said, laughing, "but I managed only 45 percent."

The fans at Giants Stadium today were a curious blend of anger and exhilaration, as if you had walked in on a family reunion in which half the cousins were united in their love for each other and hate for the other fools.

Joseph Fedak, 42, a Giants' fan from Bayonne, N.J., said he came only because he had paid for the ticket and it was a nice day.

When someone asked if Fedak liked having football back, the banker said, "You mean this?" He curled a lip toward the emerald turf, where the woebegone Giants then trailed the Redskins, 21-3. "Or do you mean real football?"

The strike should have taught the players a lesson, Fedak said. "The seats aren't full here. The fans haven't shown any great enthusiasm for it being back. I could have done without it. They're not indispensable."

"What this strike means," said Maureen Hoffman, 41, a Brooklyn native, "is that this country is falling apart. The national anthem, freedom, apple pie and football -- that's America. And we were denied it because somebody was playing politics and money. It's absurd."

Yet here she was, in her Giants' cap, and Hoffman said, "I couldn't stay away. I live in Miami now, but I had to fly up here for the game. The games are part of taking a break from life . . . I love the games. That's what makes me so furious. It was all political. You knew it would be over by Thanksgiving. They had it planned so we could thank God and watch football."

Maybe taking the temperature of Redskin fans here is not an accurate measure of what most fans think. Only a zealot goes to road games. The Redskin fans sat in Section 318 here, so high above the field that Larry Leatherbury, who owns a D.C. liquor store, brought his own TV.

"It's football," he cried out happily, waving at the tiny creatures far below. "People have forgotten about the strike already. You couldn't keep a true football fan out."

In Washington, where a road game is time to break out a new keg, some bartenders wondered where everybody was.

"It hurt me in my pocketbook," said John Sakos at the Hawk and Dove on Capitol Hill. "It drives me crazy to see grown men act like this. I know at least nine or 10 guys who spend every Saturday and Sunday in here. But not one of them is here today."

The Redskins' burgundy and gold were high in Section 318, where Mary Burger couldn't have been much happier had she walked up a few more rows and kissed an angel.

The strike didn't make sense to Burger, who with her husband owns a cabinetmaking business. "The players were wrong asking for 55 percent of the owners' gross. They could ask for more benefits and higher salaries, but not a percentage. Ed Garvey misled them there."

But she holds no grudge. "It's great to have football back," she said, and right then Virgil Seay caught a long pass from Joe Theismann, and Burger, in her Redskin cape and Redskin blouse, leaped from her seat in a whoop of joy that would have been music to Pete Rozelle's blistered ears.