What's a 9-inch square of ad space worth? If it's on the body of an Olympian, as much as $21,800.

That's what T-Mobile CEO John Legere paid on Thursday in an eBay auction for the right to put an ad on track and field athlete Nick Symmonds. The ad will appear on Symmonds' right shoulder as a temporary tattoo in the form of a logo, website URL or social media username.

On Thursday, after winning the auction, Legere tweeted, "Happy to do my part to support USA running & this amazing athlete."

He also started a Twitter poll for suggestions about what the ad should look like. The options were: "#WeWontStop (magenta T)," the American flag, and "I Run Good."

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Symmonds, 32, will apply the temporary tattoo before each race or photo opportunity. However, he'll have to put tape over it during the Olympics because of "antiquated rules" that prevent athletes from sporting tattoo ads.

"There's something so absurd about a really elite runner, world-class runner, running around with a bunch of tape all over him," Symmonds told CNNMoney. "This absurdity often raises questions."

He hopes questions about the tape will lead to a change in the rules and that athletes will eventually be able to market themselves to sponsors and display ads on their bodies during competition. He's even started an #OwnYourSkin campaign.

"My goal is to look like a human NASCAR [car]," Symmonds said.

He's worn as many as four different temporary tattoos at a time while racing.

Before the 2012 Olympics, Symmonds held a similar auction for space on his left shoulder. Hanson Dodge Creative, a marketing company based in Milwaukee, Wisconsin, won with a bid of $11,100.

However, for Rio, he switched the location of the temporary tattoo.

"When you run track and field, you're always turning left and the cameras are always on the outside of the track so the right shoulder is the most valuable ad space," Symmonds explained.

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Symmonds has held the auctions to "court sponsors and raise money to fund my Olympic dream." However, he also wants to raise awareness about how little track and field athletes are paid.

"It's important to remember that 50% of professional track and field athletes live below the poverty line," Symmonds said. "And I'm not talking about these kids that no one's ever heard of, that will never have a chance to make a team. I'm talking about Olympians and in some cases Olympians with medals around their neck living below the poverty line."

Symmonds himself isn't struggling financially. But that's because he's built a brand based on his successes. He's been to the Beijing and London Olympics and is the defending U.S. champion in the 800 meter race.

Symmonds still needs to qualify for the Rio Olympics -- the team will be selected from July 1 through July 10.

He said the Olympics generate billions of dollars for the International Olympic Committee but that the athletes receive very little -- even gold medal winners.

"It's almost like a lottery," Symmonds said. "You're just playing this game with the off-chance that you'll be -- not just great, not just an Olympian, but the best of all Olympians across all sports and then you might actually get paid. What I'm saying is that all Olympians are helping to create the show -- not just Michael Phelps, not just Usain Bolt."