The following video of San Francisco 49ers tackles Joe Staley and Mike McGlinchey singing Everybody by the Backstreet Boys in a local area bar made its rounds on social media last week. Seeing Staley, a veteran entering his 12th NFL season, and McGlinchey, embarking on his first, was yet another example of how tight-knit the 49ers locker room has become.

McGlinchey was asked about karaoke session. What led to the song choice?

"You know, it was a collaborated effort on the way over there," the rookie tackle told reporters on Wednesday. "We had just plugged in an aux cord on the car ride over and were joking around. We somehow got on the boy band theme, and 'Everybody' kind of played, and he said, 'This is the one that we're doing.' So we just kind of ran with it. It was a lot of fun."

But the relationship between Staley and McGlinchey is more than two teammates hanging out after a hard day of practices and film study. While Staley has taken on the role of a mentor, he sees McGlinchey as much more than a close teammate.

"I'm real excited about my guy, McGlinchey, in my room," Staley said during the 49ers' State of the Franchise event last month. "He's my little brother. I'm finally excited. I have a little brother."

McGlinchey was brought in to replace Trent Brown, a talented right tackle who head coach Kyle Shanahan inherited from previous regimes and never really fit the mold of a Shanahan offensive lineman. While McGlinchey and Brown, whom San Francisco traded to the New England Patriots, are the same height, the former is about 45 pounds lighter than the latter. He is more of a fit for Shanahan than Brown was ever going to be.

The first-round selection of McGlinchey was a bit of a head-scratcher, especially considering that guard was seen as the most significant offseason need along the 49ers offensive line. That was until Brown, who reportedly showed up to the 49ers' offseason program out of shape, was no longer in the team's plans. That's when the selection started to make more sense.

McGlinchey will likely replace Staley one day. For now, they are preparing to protect quarterback Jimmy Garoppolo together. What is it like for McGlinchey to have the opportunity to play with, and learn from, Staley?

"Like I anticipated before I got here, Joe is the best, and we've hit it off great," McGlinchey said. "I've been joking with everybody that he's my new best friend, I'm his, and it's been a lot of fun.

"It's great to have somebody to be close with, and also has the experience that he does, and the knowledge that he does, and be able to bounce things off of him that I'm working through and that I'm trying to do.

"He's been there for me every step of the way, not only from football but also in getting acclimated and having fun here in the Bay Area. He's an awesome guy, and I'm very, very lucky to be in the situation that I'm in."

Others have noticed the bond between the two offensive linemen. The 49ers' head coach offered his thoughts on the relationship and the group as a whole.

"I think they've been good," Shanahan said. "They're funny. It's like two giant 12-year-olds hanging out together. But, I think they have a lot of fun together. I think we've got a real good room there. Joe is obviously the veteran, Mike is the new rookie, and we've got a lot of guys in between those guys who fall right in with the group, too. I think we have a very close room in there. I think we've got a close team and it makes it a lot more fun to come into work."

While the 49ers' new franchise quarterback probably doesn't want his two anchors along the offensive line to consider a career change, he did joke that they could have a future in the entertainment industry.

"I think they need a TV show, personally," Garoppolo said. "There's a good idea behind that. Those two are a match made in heaven. They're very fun guys to be around."

While Staley has The Joe Show, McGlinchey insists he is not ready for his own online series.

"He's the guy at the forefront of that," McGlinchey said. "He's had The Joe Show running for a while now, and I'm in no place to take that away from him. He's good at what he does in that regard, and we're going to keep it that way. Why fix it if it's not broken?"

Maybe McGlinchey will take the series over after Staley decides his playing days are done. Until then, the two are content with sitting next to each other in the film room. It gives McGlinchey the opportunity to learn from one of the best in the game.

Even outside of the classroom, Staley is making sure the rookie is as prepared as possible heading into his first NFL season.

"He'll be out there right with me before practice starts," McGlinchey said. "I'll ask him to come out with me, and we'll go through footwork, or we'll go through how things need to be done and slow it down a little bit before we get into practice. And that's almost every day. He's been great with that, and he's been great with me, and like I said, I've been very, very lucky."

You didn't see McGlinchey's name a whole lot while reading offseason practice reports, and that's a good thing. It means the rookie is doing what he needs to do. McGlinchey feels he was part of a great group at Notre Dame and is thankful to be able to say the same at the NFL level.

"I don't think a lot of rookies get as lucky as I've been, to be coming in here and have the relationships that I've already had, especially with a guy like Joe, who's been there, and done that, and had great success," McGlinchey said. "I'm very, very fortunate to be in the position that I'm in and have the guys that I've had in our locker room. It's been awesome so far."