Nearly 90 minutes before tip-off, Warriors fans cram both sides of the tunnel leading to the team’s locker room. One man wears a Stephen Curry jersey and an oversize, bright blue wig. Several kids also sport No. 30 Curry jerseys. One creative lad wears a retro green Sonics jersey bearing Kevin Durant’s No. 35.

They are here for a distinctive spectacle: the tunnel shot.

This is a measure of the Warriors’ uncommon place in the sports galaxy. All these people arrive early to games at Oracle Arena, rush toward this spot and jostle for position to watch Curry hoist what amounts to a circus shot (and get autographs).

His pregame routine has become a wildly popular show, the basketball equivalent of power hitters launching majestic home runs in batting practice. The punctuation comes when Curry catches a pass from security guard Curtis Jones and lofts a long shot from the tunnel — while nearby spectators take video on their cell phones.

The shot dates to 2013, but the surrounding hoopla has soared into another realm the past season and a half, since the Warriors won the 2015 NBA title. Club officials even plan to auction Jones’ role to the highest bidder once a month starting later this season, allowing a fan to pass the ball to Curry; proceeds will go to the Warriors Community Foundation.

Part of the tunnel shot’s appeal is its funky, playground flavor. Few people would make it as often as Curry does, naturally, but who hasn’t tried a crazy, improbable shot while playing H-O-R-S-E?

“It’s unusual,” said assistant coach Bruce Fraser, who works with Curry on the court before games. “If you watch Steph’s warm-ups, you’ll hear some ‘oohs’ and ‘ahhs,’ but nobody’s really locked in. They’re watching him and other stuff.

“For this one, they’re locked in. They know the tunnel shot. It’s just him, and they know it’s coming.”

At first, Curry didn’t think much about the shot or its impact. Then, during the NBA Finals against Cleveland in June 2015, the size of the stage — and the power of social media, with videos quickly going viral — made it more of a true happening.

This seeped into his head a bit, when he realized many fans reached the arena early specifically to watch him take the tunnel shot.

“I hadn’t really realized people were making an effort to do that, because it’s something I had been doing for a while — as part of my routine, not for show,” Curry said.

“When I heard that, I don’t want to say I felt pressure, but I thought, ‘Wow, they came here to watch this shot. It’s part of their experience. And it would really suck if I missed all five shots tonight, because they came to see it.’”

Curry got the inspiration from former teammate Monta Ellis. Ellis sometimes tried trick shots during practices or before games, most notably shooting backward over his head from the corner in front of Golden State’s bench.

Curry took the idea a step farther — actually several steps farther, off the court. He and front-office employee Patrick Sund, who is no longer with the team, placed a good-natured bet on whether Curry would make the shot in his first three attempts.

He “won” if he made one; if not, Sund won. They kept a running tally and settled up at the end of the season. And, no, Curry did not come out ahead.

“I think I fronted his summer vacation a couple of years,” Curry said.

The wager helped Curry, a creature of habit, build the shot into his pregame routine. He trots onto the court about 90 minutes before game time and finds a familiar rhythm: fast-paced dribbling drills, short high-arcing shots, three-pointers and halfcourt shots. Curry takes about 125 shots in all.

Then, before he signs autographs and sprints up the tunnel, he stops for one more ritual. Curry launches the tunnel shot 45 to 50 feet from the basket, and about 5 feet behind it.

Jones, the security guard, chooses a ball during Curry’s warm-ups and stuffs it under the last seat on the bench. Jones rubs the ball for “good mojo” and delivers it to Curry with an underhand toss.

Curry gives himself five attempts to make the shot. If he misses, the ball boys chase down the specific ball Jones picked earlier; Curry really doesn’t care, but Jones is particular about this.

“I’m in his world at that point,” Curry said.

The shot is unlike any he would try in games, given its weird angle and background. Those factors make the shot extraordinarily difficult, even for a player widely regarded as the best long-distance shooter in NBA history.

“It looks like you’re looking into an ocean of seats, way back in the back,” Curry said. “There’s a different depth perception versus shooting it on the court, even in the corner.”

As for standing 5 feet behind the basket, he said, “That brings the backboard into play, and I hit that a good amount of times. In order to swish it, you have to almost hit the backboard.”

Curry, an avid golfer, agreed when it was suggested the shot is similar to a daunting golf shot. Just imagine a small green alongside a pond, with the hole tucked near the water. Or, as Curry called it, a “sucker pin.”

General manager Bob Myers (a former UCLA forward), asked if he could make the tunnel shot, went with the golf analogy.

“If I’m trying it, that’s when they would push the gallery back,” he said. “They’d take the ropes and say, ‘All right, sir, Myers is shooting now, take a few steps back.’”

Curry estimated he’s on pace to make one tunnel shot before about 60 percent of Golden State’s home games this season. That doesn’t mean he always sinks it on his first try; it just means he makes it once in five or fewer attempts.

By his calculation, he probably will finish this season approximately 25-for-160, which computes to 16 percent. This meshes with a small snapshot recently, when Curry made his first shot Jan. 18 before a game against Oklahoma City and missed all five tries Feb. 1 before a game against Charlotte.

Last week’s game against Sacramento included a different twist. Visiting teams choose which basket to use in each half, and the Kings are one of five or six NBA teams that prefer to play offense in front of their bench in the second half (at the south basket). All other teams prefer to play defense in front of their bench in the second half.

This means Curry and his Warriors teammates usually warm up on the north basket, in front of their bench and the tunnel. For the Sacramento game, though, they had to warm up on the other end of the court; so Curry flung one 95-plus-foot “shot” from the edge of the tunnel all the way to the south basket (there is no tunnel on that end of the court). He hasn’t made one of these ultra long-distance shots; this time, the ball bounced off the top of the backboard.

That’s not really the spectacle fans have come to expect.

Ron Kroichick is a San Francisco Chronicle staff writer. Email: rkroichick@sfchronicle.com Twitter: @ronkroichick