LeBron James #6 of the Miami Heat looks on after a play against the Indiana Pacers during Game Five of the Eastern Conference Finals at AmericanAirlines Arena on May 30, 2013 in Miami, Fla. - 

If you're watching a Miami Heat home game, do not adjust your television's brightness.

The glare you are getting is part of the team's White Hot campaign. For all of their home games during the playoffs, the team hands out a white T-shirt to all 20,000 fans who come through the gate.

"We use them to get the crowd excited about what the campaign is, which is wearing white to the games," says Michael McCullough, the Miami Heat's executive vice president and chief marketing officer. 

"For us, it really isn't so much about wanting our fans to wear our T-shirt in the building,” he says, “We give those T-shirts out because it's really a marketing and a branding opportunity to us, outside of the arena more so than inside the building."

Other NBA teams have also gotten into the T-shirt bonanza. At Indiana Pacers games, the crowd is awash in yellow. Fans of the Oklahoma City Thunder formed a sea of powder blue.

Steven McDaniel is a professor at the University of Maryland, specializing in sports marketing. He says there's more to it than just that.

"You're showing fans that this is the type of in-game experience you can get, because all of the sports leagues now are facing a challenge of getting people in seats,” he says.

According to McDaniel, the T-shirt giveaways also give teams a chance to reward their best fans, and present a unified front for a national TV audience.

"You have shown by panning the crowd that all of these fans are involved in a game because they have put their T-shirt on over what they're wearing, and that T-shirt is a sign of solidarity,” says McDaniel.

And that's particularly important in the NBA, he says, because it lacks the tradition many college teams already have.

Meanwhile, outside the Heat's home at The American Airlines Arena in downtown Miami, Carl Jacobsen wears one of those free T-shirts. He says he relies on the giveaways as part of his wardrobe.

"Yeah. I've missed three games in 18 years for the Heat,” Jacobsen says.  “All my T-shirts, I don't pay, I just rely on all the giveaways."

But not all NBA teams feel the same way about T-shirt marketing. Until now, the Western Conference champion Spurs have chosen not to hand them out to their fans in San Antonio.