Knicks rookie Ron Baker started the “Three-Scope’’ five games ago — an invention that embodies the bench’s high-energy, collegial antics.

Whenever a Knick drains a 3-pointer, Baker is up on his feet, his fingers forming two circles that he peers through.

“It’s the Three-Scope,’’ Baker told The Post. “When someone makes a 3, the Three-Scope gets dialed in on that person. I’m trying to bring good energy and vibes from the bench. It’s a good way to stay in the game. Or maybe I’m just a goof.’’

No, it actually is appreciated and encouraged by Knicks coach Jeff Hornacek. He was unaware of Baker’s innovation but loved it just the same.

Since the preseason opener in Houston, Knicks players on the bench have acted like a high school team, standing up until the team’s first basket is made. That also didn’t come from Hornacek.

“Something they’ve done on their own,’’ Hornacek said. “I didn’t tell them to do it for the first basket. I wanted to make sure from the first game they get up on dunks and 3-point shots.

“It’s great what they’re doing. When you’re on the bench and just sitting there and all of a sudden your name is called, you’re not going to be ready to go. It’s a way to keep you involved in the game. I think it’s great all guys on the bench are doing that.’’

The defending-champion Cavaliers have their own way on the bench. A video surfaced of LeBron James and Kyrie Irving playing rounds of flip-the-water-bottle — the new millennial stunt to pass time. Except this was during fourth-quarter garbage time at the Garden on Wednesday. The goal is to get the half-empty bottle to lands on its base and stand.

One clip showed the bottle rolling onto the court during play and James frantically lunging to retrieve it. Rooting for his mates on the court wasn’t evident.

“That doesn’t concern me,’’ Carmelo Anthony said. “My concern is how we play.’’

On the flip side, there is the Knicks’ bench act of being involved in the on-court action. The new tradition was started by Joakim Noah, impromptu. Out with a hamstring injury, Noah decided to stand at the opening tip in Houston, and all the players on the bench followed suit. A new tradition was born.

Noah doesn’t like to take credit but said, “It’s a good look, though.’’

“I think it’s just a sign of respect to the starters,’’ said Brandon Jennings, normally part of a bench is the seventh-most effective in the NBA, with a plus-minus of 5.6. “It’s showing we’re engaged and staying with you guys until you make the first bucket. In general we got good guys who get along on this team. This might be something small, but that goes a long way for our team what we’re trying to accomplish.’’

Standing until the first basket is a tradition in many college basketball arenas for the fans. Only at Oklahoma City has it become a staple, with Thunder fans noted as the loudest in the NBA.

None of the Knicks reserves recall doing the stunt on any other club, even in college or Europe.

“First team I’ve been on we’ve done that,’’ Jennings said. “I’m used to starting, but I don’t recall it. It’s definitely different.”

Knicks rookie Mindaugas Kuzminskas, the cheerful Lithuanian who played in the Spanish League in recent years, said in general the bench hijinx are much more electric than in staid Europe.

“Here, everything is different, the bench is different,’’ Kuzminskas said. “We have so many guys on the bench and all those coaches. Here, the support of the players is bigger and acting more emotional on the bench. In Spain, [at an] important moment, everyone is up. Here the celebration is different. We don’t have the jokes when someone hits a 3 with [Baker], they’re aiming. It’s more conservative.”

Will Kuzminskas attempt to top Baker and come up with his own 3-point salute?

“I’m just shy and conservative guy,’’ Kuzminskas said, laughing. “I just clap. But standing up is a nice tradition.’’

The players don’t talk about their stand-up-until-the-first-basket ritual. In fact, some of them didn’t even know how it started.

“It’s what we do,’’ Justin Holiday said. “I think it’s cool. My first time ever doing it. We like to roll with it. It’s a good thing — dudes cheering the team, makes things fun to get excited for everybody else. Even if you’re not in the game, you’re having a good time on the bench.’’

Baker said he felt he needed to spice things up, but the guard from Wichita State is enjoying the stand-up routine, especially when the first basket is a triple.

“Coach is all about energy,” Baker said, “and we’re trying to give energy from the bench.”