Social media is a way for fans to get inside, to see professional athletes behind the scenes. But in Marquette King’s case, it’s a means to get out, a chance for the Raiders’ punter to break free and express himself.

Three years after the pressure had gotten too great, King is now a bona fide celebrity. And its not because he is one of the better kickers in the league, but because he is its unlikeliest social media star.

King tells his followers on Twitter everything. Except for the times his arms used to tingle and go numb after games.

“I used to have panic attacks because I was so hyped up from the game,” King said, sitting in the Napa Marriott courtyard last week, before a training camp practice. “It was tough driving home, and then I wouldn’t be able to get to sleep until 3 in the morning.

“And people would say, ‘But you just punt the ball.’ … OK, give me a 45-yard punt with hang time and aim it for that corner. All right, then.”

Back then he couldn’t, or didn’t want to, get the words out when reporters tried to interview him after his best games. King, 28, no longer avoids the media, but today he is trying to escape a mob of autograph seekers as he looks for a quiet place for this interview.

The once-shy undrafted punter from Fort Valley State has 282,000 followers on Instagram and 161,000 on Twitter. He flooded both those and his Facebook account with daily posts this offseason. From punting footballs into basketball hoops and pizza floats into pools to traveling around the country and appearing at Comic-Con or other sporting events or concerts, King has been everywhere and done everything the past seven months.

And he’s shared it all with the fans.

“The cool part about social media is that people can see you’re not a robot,” King said. “I remember when I used to watch Mike Vick play, I would think that he would play the game, go into the locker room and plug his back into the wall until the next Sunday.

“Fans get to see that we have a life, too. We’re normal, just like them. That’s also the fun part, showing them that I do the same stuff that they do.”

Most fans, though, don’t wear Power Ranger masks in public, or take videos of themselves swiping strangers’ 49ers hats at restaurants. King also punted a birthday cake for Derek Carr on social media.

“I do it to make people’s days better,” King said. “Humiliate myself or do something silly to make somebody laugh.”

King, who spoke at Twitter two weeks ago about building his brand, was scared when he first started posting frequently a little more than a year ago.

“You just have to be smart about your decisions, about what you put out,” King said.

One teammate and some fans didn’t think one of his decisions this offseason was very smart.

In the regular-season finale on Jan. 1, Broncos cornerback Aqib Talib ripped off and broke Raiders receiver Michael Crabtree’s gold chain in what he later said was a premeditated move. Crabtree was upset about it, largely because Talib wasn’t penalized.

Fast forward a month, and King was working the Pro Bowl sideline, doing social media posts for NFL.com. He had Talib, playing in the game for the AFC, tug at a chain from King’s neck, and the two posted the picture on Instagram and Twitter and laughed about it.

King soon deleted his post when Raiders linebacker Bruce Irvin posted a comment, saying “No loyalty SMH.” If Irvin was shaking his head, many Raiders fans were doing a lot more, ripping King for his act of treason for weeks on social media.

“It was nothing against Crabtree at all,” King said. “It came out the wrong way, I guess. People try to create a story out of nothing.

“My intentions were more to make fun of (Talib). He is going around snatching people’s chains and stuff. I was just trying to find a way to make light of the situation. At the end of the day, when this game is over, are you going to hate somebody for what they did in a game? This game doesn’t last long.”

King doesn’t think Crabtree had an issue with the post, but knows better than to tell the 6-foot-3, 250-pound Irvin to calm down.

“He is like one of those ‘Mortal Kombat’ versus DC characters,” King said. “Big as I don’t know what. … But we do a good job of not letting stuff off the field bother us in the locker room, so it’s all good.”

King just goes about his business, kicking the ball into the clouds and making fans laugh. He, for one, is not surprised he has gained so many followers so fast.

“Not really, because as long as you’re organic and being yourself, people are going to latch on to you,” King said. “That’s the cool part.”

King will often type up posts or tweets and leave them on his screen for 5-10 minutes before publishing — to give himself a chance to change his mind, and sometimes bring in a friend as a filter or for approval.

“Because it’s fun to have edgy stuff and stir things up a little bit, but not to the extreme,” King said. “I do like messing with people, though.”

Let’s face it, trolling for a reaction on Twitter can be fun.

“Yeah, it is fun,” King said. “A lot of people get so caught up in what you’re doing or why. They think that people are what they post on social media, but sometimes it’s not real. It’s fun to mix it up, and then people think they might know what you’re thinking, but they really don’t.”

Even teammates who are around him a lot don’t know what King is thinking sometimes.

“He’s … he’s a tough one … to dial in and figure out who he is,” long snapper Jon Condo said. “He’s having a fun time, and the social media stuff gets his mind off football, gets his mind off thinking about always having to perform. There’s a stress level that you have to be able to manage.”

Condo said King works very hard to be the best punter in the league. (He led the NFL with 38 punts of 50 yards or more last season.)

“And he always has a smile on his face now,” Condo said. “He really enjoys the social media stuff. He’s out there for everybody. … It’s fun to watch him interact with strangers in public.”

King said he and Marshawn Lynch enjoy engaging random people on the street. King and the no-longer retired running back have a mutual friend, and King would have fans going crazy when he had posts with Lynch before he signed with the Raiders this summer.

“Marshawn brings a unique personality,” King said. “He brings the edginess. He’s definitely what a Raider stands for. He’s real, organic and a wrecking ball. He is definitely going to be a huge part of the team.”

Lynch famously doesn’t have a lot of use for the media, much like King didn’t used to.

Media relations senior director “Will Kiss was on me a lot about talking to the media and just being myself,” King said. “Before that, I felt like I wasn’t going to have control of the situation. You reporters have a lot of power. You could say Mar-cuet did this and everybody believes you. … ”

King was asked why he said his name Mar-cuet when it’s been pronounced Mar-ket his entire five-year career.

“Tomato, tomahto,” he said. “Depends how I feel. Or if people say it one way, I just roll with that. … I actually prefer ‘Your Highness.’”

King went on to give another reason for his former reticence. He explained that whenever he kicked well early in his career, and felt good about it, he did worse the following week. So he tried to stay even-keeled, and that included turning down interview requests after good games.

King lifted that policy last season, and then got so excited things were going well that he lost his mind a couple of times.

In a Dec. 4 game against the Bills, he picked up the official’s flag (the penalty had been against the other team) and started doing a country hoedown dance with it.

“I really didn’t know I couldn’t pick up the flag,” King said, smiling. “I swear. I was surprised when they gave me a penalty.”

The following game, after the Chiefs’ Tyreek Hill ran a punt back for a touchdown, King chased him down in the end zone and bumped him. Two weeks, two unsportsmanlike conduct penalties against the punter.

“He was so fast,” King said. “I got emotional about it and felt I had to chase him down after. I take punting seriously, and he and I were chatting back and forth before he ran the punt back. That sucked. Because he ran that back just like he told me he was going to.

“All I could do was chase him down. It hurt … because I let the team down when I did that.”

Chiefs tight end Travis Kelce then went viral after the penalty, mocking King after Hill’s touchdown with a horse-riding simulation that King had done in an earlier win over the Denver Broncos.

Of course, King and Kelce later became friends over social media at the Pro Bowl.

“I love that guy,” King said. “I love everybody, man.”

Vic Tafur is a San Francisco Chronicle staff writer. Email: VTafur@sfchronicle.com Twitter: @VicTafur

Cooper sits out practice

Raiders wide receiver Amari Cooper sat out his second straight practice Saturday with an undisclosed injury.

Cornerback Sean Smith, a starter last season, lined up with the second team again, with TJ Carrie taking his spot.

Reserve safety Keith McGill was seen after practice using crutches, a new development.

— Vic Tafur