CHICAGO — The most popular grandpa in Chicago these days just might be a 39-year-old with three young children who happens to play for the most dominant team in the majors.

Oh, and he does not actually have any grandkids.

Even so, David Ross might as well be a grandpa by baseball standards. And as his career winds down after 15 years, he’s getting a grand send-off with the Chicago Cubs. While a long-suffering franchise eyes its first World Series championship since 1908, a lifelong backup catcher is being treated like a star on his way out the door.

“I was at dinner last night,” Ross said. “Somebody yelled across the restaurant, ‘Hey grandpa!’ when I walked in. I’m like, ‘How we doing? How’s it going?’ A lot more attention. It’s unique, different for me.”

Yes, it’s quite a time to be “Grandpa Rossy.”

“Grandpa Rossy?” Well, that started in spring training.

Kris Bryant and Anthony Rizzo were at dinner with Ross and some other players when the two young sluggers decided to have some fun and open an Instagram account documenting his final season.

Grandparossy_3 started with three pictures posted on Feb. 21 — of Ross posing at a sporting goods store with a Cubs shirt and mitt in one hand and pants, batting gloves and knee pads before his “last first day”; of a black-and-white Ross baseball card from when he was with the Los Angeles Dodgers in a nod to his age; and of the three of them at a Phoenix Suns game. The account has grown to one with 136,000, and the retirement tour spurred such a demand that the Cubs are selling Ross t-shirts at Wrigley Field for the first time since he joined the club before last season.

“It’s his last year playing baseball,” Bryant said. “We wanted … to make him feel really special, that we really care about him and are gonna miss him.”

Even better, they’re having fun along the way.

The Instagram account became a vehicle for Ross to post pictures from the road and of his family and teammates. There are shots of him playing, working out and hanging with Rizzo in Las Vegas.

There are videos, too. One from spring training shows Ross in a “G-PA ROSSY” No. 3 jersey walking hunched over in the clubhouse using a bat like a cane as Rizzo and Bryant help him.

“Almost there,” Rizzo says.

“You can do it,” Bryant chimes in.

In another, Ross and Rizzo perform an acoustic rendition of Vanilla Ice’s “Ice, Ice, Baby,” with Ross on guitar and vocals and Rizzo on a conga drum.

The Cubs organization also jumped on the “Grandpa Rossy” phenomenon and produced a series of videos with Ross to generate All-Star votes for his teammates.

In one, Grandpa Rossy uses a rotary phone to implore fans to dial “#votecubs” and call in their vote. In another, he encourages them to fax it.

Teammates also gave Ross a motorized scooter during spring training to help him get around.

“At first, we kind of felt bad calling him grandpa,” Bryant acknowledged. “He’s like 38 years old. That’s pretty young for a normal person. He’s enjoyed it.”

It hasn’t been all jokes and gag gifts. There have been sweet gestures, like this one compliments of Jason Heyward: Suite upgrades for Ross and his family on the road.

For Heyward, who signed with Chicago in the offseason, it was a way to thank someone who helped him when he was breaking into the majors with Atlanta six years ago. He learned quickly that Ross had a way with words, like that time the Braves were playing an exhibition game against the Mets before his rookie season.

Heyward took his turn in batting practice and went inside. Ross wanted to know why he wasn’t shagging fly balls instead.

“If there’s something that’s not happening and needs to happen, he’s the person to say something about it the right way,” Heyward said. “When he speaks, it’s probably a good idea to listen because he’s saying something that’s gonna help you as an individual and he’s definitely saying something that’s gonna help the team.”

Jon Lester, who played with Ross in Boston, said, “He knows how to push you the right way.”

That in part helps explain why the Cubs consider Ross, a career .229 hitter on his seventh team who has never played in more than 112 games and has logged more than 200 at-bats only two times, so important.

It goes beyond the raw numbers. He is a steady hand behind the plate and in the clubhouse, a player who won a championship with Boston in 2013 and is trying to help a team loaded with stars from Bryant and Rizzo to Jake Arrieta and Lester finally bring home a championship to Wrigley Field.

“I look back on what I bring and my skillset and how I got this much time in the major leagues, it blows my mind,” Ross said. “I try to appreciate that and not take that for granted.”

He is someone manager Joe Maddon saw as a perfect fit from the moment he found out. Maddon was driving around Tampa and pulled into a parking lot to call Ross.

“Fun, passionate, aggressively wanted to win, great teammate. All that stuff came through in that phone conversation,” Maddon said.

Now, a career that started with the Los Angeles Dodgers in 2002 nears the end, Ross is soaking it all in and having some fun along the way. He started keeping a diary documenting the season in a leather notepad his wife gave him and now makes a few entries a month on his phone, instead, usually during flights.

“It’s time to go home, it’s time to be a family, it’s time to start a different chapter in my life,” Ross said. “I love baseball, don’t get me wrong. I love playing, I love competing, I love these guys. There’s a perfect atmosphere here.”