Redskins fans celebrate the game winning touchdown by wide receiver Pierre Garcon against the New York Giants at FedEx field on December 3, 2012 in Landover, Md. (Jonathan Newton/THE WASHINGTON POST)

Superstitious Redskins fan Chris Gellner has known for weeks what he’ll put on before driving to FedEx Field from Centreville on Sunday: The same stenchy game-day gear he’s been wearing — without washing even once — since his beloved football team stopped losing in early November.

“My girlfriend says they smell terrible,” Gellner said of his rancid Ryan Kerrigan jersey, Sean Taylor T-shirt and breast-cancer-awareness-pink wristband and socks, a combination that’s on a Hazmat-worthy six-game winning streak. “I’ll admit the socks are absolutely horrendous now. But you can’t wash your clothes when you’re on a roll. It’s bad luck.”

As the Redskins brace for Sunday night’s regular-season-ending, division-winner-deciding NFC East showdown against the dreaded Cowboys, Washington’s most ardent football fans are getting in touch with their inner superstitions.

Who cares whether or not their rituals have truly brought good, metaphysical fortune to the Redskins? (They have not, researchers can assure you.) In the strange calculus of sports fanaticism, shelving those superstitions now — in the midst of a major winning streak — simply does not compute.

So Tyler Duchaine and his family will continue to do push-ups every time the Redskins score — one for each point. “Since we’ve been doing them, the Skins haven’t lost,” said Duchaine, 23, of Alexandria.

Doug McKinney, a Comcast SportsNet producer, will continue to avoid his razor: He hasn’t shaved since the winning streak began in November. “My parents had to warn my family that I was showing up to Christmas with a gnarly beard,” he said.

Johannes Schneider will begin game day with an edible superstition: “We have one of those toasters that imprints the Redskins logo into the bread, and I have to have at least two slices of Redskins toast for breakfast,” he said.

Then, he will put on his lucky Redskins hat and socks and drape the dog in her lucky team jersey. By kickoff, Schneider, 31, a sports management major at Winthrop University in Rock Hill, S.C., will be seated in his spot on the left side of the couch, and he will put his rally towel next to him. He will swing it when Washington’s defense is on the field.

“I’m a very superstitious guy,” he said. “I don’t really believe my superstitions have an impact on the outcome. But if we lose and I don’t do something that day? I definitely blame the loss on myself.”

Sound crazy? To Daniel Wann, it just sounds familiar.

Wann is a Murray State University professor who has spent a quarter-century studying the psychology of sport fandom. He has just co-written a major research paper on fan superstitions in which more than 40 percent of the 1,661 people sampled said they had at least one behavior — from movements and vocalizations to how they chew their gum and wear their hats — that they believed had an influence on their favorite team’s performance.

“People say two things about their superstitions,” Wann said. “I know this is silly, but I still think I have to do it. Or, I know this doesn’t matter, but maybe it does matter. It comes down to the fact that they are helpless and just want some kind of control over this thing they care so much about.”

Lest you think it’s just men who participate in such rituals, meet Jennifer Rubenstein. She’ll be wearing the socks.

The knee-high, teal-blue socks emblazoned with the Superman logo are identical to the pair Robert Griffin III wore when he won the Heisman Trophy. Rubenstein ordered some after Griffin was drafted by the Redskins and started wearing a pair at home during the preseason. They were dirty when the Redskins lost to Cincinnati in September. She tossed them in the wash after the loss to Atlanta in October. The Redskins won their next game against Minnesota.

Rubenstein, 31, a medical speech-language pathologist from Arlington, came to the only plausible conclusion: The socks had to be clean. Rubenstein did not question that message, even though it ran counter to the one sent to countless other Redskins fans.

“Since college, I haven’t washed my jersey after a Redskins win — but we’re in uncharted territory here,” said John Fallon, a Herndon native now living in New Orleans. His Chris Cooley Redskins jersey — unwashed since just after the Nov. 4 loss — smells like beer and cigarettes and fried shrimp po’ boys. He keeps it at the end of his couch, which is also one of his superstitions. “It’s my contribution to the streak. But it reeks. My dog won’t go near it. ”

Such superstitions are at the center of a recent Bud Light ad campaign about sports fanatics. In one spot, football fans rotate their beer bottles so that all the labels face forward — all the better to help the kicker make a field goal. Another ad features a montage of superstitions, from synchronized thumb-twiddling and foot-tapping to arranging beer cans into a horseshoe. The slogan: “It’s only weird if it doesn’t work.”

“That is me 100 percent,” said Gellner, the Redskins fan with the rancid Kerrigan jersey.

On Sunday, Gellner will become singularly focused and irrationally superstitious. He will drive to his usual spot on the edge of the Green B3 lot and grab his bottle of Crown Royal. “I’ll say, ‘Here’s to you, FedEx,’ then tap my truck with the bottle and take a shot.”

Once inside the stadium, he will lock eyes, as usual, with his seat neighbor. Then, during the game, Gellner will remove his hat and turn it around twice each time Dallas scores.

“I know it sounds pretty crazy,” he said. “I know somebody will tell me that what’s going to happen is going to happen. But it’s what keeps me going. It gives me hope that we’re going to win. And we’ve been doing fine. I think it works.”