The Steelers' safety first opened a Twitter account in 2010 before the start of the football season, figuring it could be a fun way to communicate with fans.
Less than a year later, Clark had enough and shut down his account.
"I've been on there and had people use the N-word to address you and cuss at you and say things about your family," Clark said. "I've had people around Pittsburgh when they see you out having a drink with the boys say 'Oh, Ryan Clark is doing such and such.' It just became almost an invasion of your privacy in certain ways, and to me the positives from it weren't enough to outweigh that."
NFL players are starting to experience the repercussions of using Twitter. The website and social networking service is less than 5 years old, but in the past two years it has become one of the fastest-growing forms of communication.
Clark's story of quitting Twitter hits close to home because his Steelers teammate, Rashard Mendenhall, is among the latest group of high-profile athletes to get into hot water through social networking. Last week Pittsburgh's starting tailback and leading rusher made a series of controversial tweets regarding the death of Osama bin Laden and the events of 9/11, which caused a significant backlash.
The Steelers subsequently issued a statement and Mendenhall followed with a clarification and apology. But it was too late. A few days later, Mendenhall lost his endorsement deal with Champion and took a huge blow to his popularity -- all over a few 140-character messages.
"Some of these guys don't realize the ramifications down the road," said George Regan, who is chairman of Regan Communications Group in Boston. "You're playing with dynamite. It's very dangerous. They have to treat that as if they're in a press conference before a microphone."
Clark agreed that players need to be more aware when using Twitter.
"A lot of times you're sitting at home or sitting in a restaurant when you do these things, and you're not paying as much attention that it's going to go out to all the people that it does and be scrutinized in that same way," Clark explained. "But every time you step in front of a mike or step in front of a camera, you know tons of people are going to have access to this. Tons of people are going to see it."
New Orleans Saints running back Reggie Bush also stirred up controversy via Twitter this week. On Monday, Bush hinted that he's not too concerned about the NFL lockout, which is a sensitive subject in the sports world for fans, players and owners.
"Everybody complaining about the lockout! Shoot I'm making the most of it! Vacation, rest, relaxing, appearances here and there! I'm good!" Bush tweeted. "Right about now we would be slaving in 100 degree heat, practicing twice a day, while putting our bodies at risk for nothing."
Bush later explained he was joking after receiving plenty of negative backlash from his Twitter followers. Tone is something that's very difficult to accurately gauge on Twitter, which Bush learned the hard way.
"You have to be careful about humor," said Chris Rosica, head of Rosica Public Relations in New Jersey. "I would avoid humor in social media, as well as traditional media, because humor can be misconstrued. It's all in the perception of what you say, and online you don't really know the tone of voice."
Everyone is entitled to express opinions. But just as free speech is one of our country's greatest perks, it also can provide major risks for athletes.
The NFL has become America's most popular sport, which helps brand many of the league's good players. Athletes can not only make a lot of money for their athletic ability on the field but their marketability off the field, as well.
Mendenhall, for example, agreed to a 4-year contract extension with Champion on May 1 before the plug was pulled on his endorsement a few days later. Mendenhall essentially took money out of his own pocket through Twitter, which is not a good practice, especially during the NFL lockout.
With the amount of big bucks being spent to market athletes, major companies also are keeping tabs on social media.
"We have a guy here who monitors it all the time and is really into Twitter and following what our players say," Reebok NFL marketing manager Kurt Evans said. "We sign our guys and we have moral clauses in our contracts, and when an issue comes up, we debate what to do about it."
Twitter also can become a headache for public relations staffs for NFL teams, player agents and publicists, who are hired to protect the image of the team and the player. Twitter is often a direct bridge to the brain that cuts out the middle person. It only takes seconds to post the first thought that comes to mind, and once it's out there it becomes fair game for the media and public to consume.
Rarely does an athlete stop to seek advice before tweeting. Although in many cases it's not necessary, Mendenhall certainly could have benefited from consulting with his representation before expressing his controversial views last week. Chances are Mendenhall would have been advised to stay away from the touchy topic of bin Laden and 9/11.
"The problem with Mendenhall is he was giving opinions," Rosica said. "You can really hurt yourself because everyone is going to have a different opinion."
The NFL is still trying to get a handle on Twitter. Last year the league put guidelines in place for the first time during games.
Players cannot tweet or use any form of social media 90 minutes before kickoff until the end of post-game media sessions. Last August Cincinnati Bengals receiver Chad Ochocinco, who has nearly 2 million followers, was fined $25,000 for breaking the league's Twitter policy in the preseason. But too many restrictions could raise questions about the NFL hindering free speech, leaving most of the onus still on the players.
Thousands of athletes from various sports are very much into social networking. Therefore, it's likely just a matter of time before the next high-profile player has a Twitter controversy.
But Mendenhall and Bush provide the most recent cautionary tales of tweeting gone bad. The biggest lesson athletes can learn from this is to think before you tweet.