The Red Sox entered the week tied for third in the American League with 13 home runs. That means there have been 13 laundry cart rides in the dugout this season.

Ah, yes, the laundry cart ride. That lighthearted ritual exemplifies how much fun the Red Sox are having during their hot start to the season.

Actually, it started last year. Toward the end of a miserable 24-36 season, the Sox needed something to make them smile.

On Sept. 13 at Tropicana Field, catching instructor Jason Varitek — who is now the team’s game-planning coordinator — noted a random laundry cart in the dugout and wondered what it was doing there.

The general consensus is that backup catcher Kevin Plawecki — with input from Varitek — decided that a player would go for a ride in that cart after going deep.

The second batter in that Sunday afternoon getaway game, Christian Vázquez, put one over the fence. And from there, a ritual started that has brought a lot of smiles ever since.

J.D. Martinez had three cart rides during his three-homer day Sunday in Baltimore.

“It’s just fun,” Martinez said. “It’s just something stupid but fun. We enjoy it. Any little thing we can do to create some camaraderie with the guys and kind of bring everybody tighter and closer together is fun.”

For a big guy like Martinez, getting out of the cart can be a bit of an adventure.

“We get a new cart at every park,” Martinez said. “This one was too deep. It was freaking really deep. I was like, you guys are going to have to carry me to get me out of this thing. We had to fill it up with towels.”

Rafael Devers hit two missiles for homers Sunday, which meant he got a couple of rides also. And the smile on Alex Verdugo’s face during his cart ride after a three-run homer Sunday — his first longball of the season — was priceless.

Though Red Sox manager Alex Cora wasn’t with the Red Sox last year, he watched every game on television and could see the enthusiasm that was generated from the laundry cart. He encouraged his players to keep it going this year.

Though Christian Arroyo isn’t known for his home runs, he got the second ride on that September Sunday last year, homering in the sixth inning that day against the Rays.

“It was just one of those things last year. We were trying to have some fun in a situation that wasn’t the most ideal, and we just carried it over to this season,” Arroyo said. “We’re definitely having fun with it. It’s fun when guys hit homers. When you’re running around the bases you’re not thinking about it, you’re thinking about the swing you made, but then you get to the dugout and see that laundry cart, it just takes it to the next level, the next step of, ‘Wow, we’re really having fun.’

“We’re going to keep rolling with it. It’s just one of those things we enjoy doing. Hopefully there’s a lot of those this series and a lot more of those the rest of the season.”