ATLANTIC CITY, N.J. — Will "Sleepy Joe" be the first derisive nickname President Donald Trump bestows upon Joe Biden?

Will either candidate wear a mask onstage? How many times will Biden say "Barack Obama?"

Will Trump say "fake news" or "China" more often? And will there be a "malarkey" anywhere?

Some of the country's largest sports betting companies are offering free-to-play contests in which viewers predict what will happen at Tuesday's presidential debate for a chance to win real money or prizes.

It's the latest example of how the fast-growing sports betting industry is making inroads into mainstream popular culture. As of Monday morning, nearly a half-million people had entered contests run by FOX Bet, DraftKings or FanDuel.

So if you're up on Democrat Biden's favorite sayings, you could win some money, God love ya. And if you think you know what Republican Trump is about to say, you can predict it very strongly.

"Politics is a really interesting thing to try to predict," said Alex Baker, a 34-year-old Chicago man who runs a fantasy sports website. "A lot of times the betting markets do the best job of predicting what the outcome of the election will be in real life."

No jurisdiction in America has legalized betting on elections, an activity that's legal and widespread in Europe. But because contestants don't risk anything of their own to enter — and this is a debate, not an election — it's all legal. FanDuel and DraftKings each offer a prize pool of $50,000 to be split among top finishers; FOX Bet's pool is $25,000.

After downloading the relevant app, contestants make choices in the same way that sports bettors gamble on things that will or won't happen during a game; such wagers are called propositions, or "props" for short.

But instead of predicting whether Seattle Seahawks quarterback Russell Wilson will throw for two or more touchdowns in a game (always a good bet, by the way), contestants in the debate pools will predict things that might be said and done on the stage.

One question asks whether Trump and Biden greet each other with a handshake, fist bump, elbow bump, an "air high-five" or no physical greeting at all.

"I don't think they're going to do anything, not fist bump or shake hands or anything," said one contestant, Matt Marino of Houston, a 36-year-old executive with a pipeline logistics company.

Among his other predictions: Biden will wear a mask onstage; Trump won't. Biden's most frequently uttered words will be "Barack Obama," while Trump will say "China" more frequently than "fake news."

Baker is confident Trump will utter the words "law and order" during the debate because "that's a large theme of his speeches lately."

He also thinks Trump will say the word "China" before Biden does, but is less sure whether the former vice president will mention his Corvette.

Part of the idea behind the contests is to interest those who don't currently bet on sports, get them familiar with the concept on free games and hopefully win them over as paying sports betting customers.

"As we've learned from states in which we operate legal sports betting, interest in wagering stretches beyond sports," said Kip Levin, interim CEO of FOX Bet. "We also know that a lot of customers love the fun aspect of bragging rights with their friends and family, and that applies here, too."

FanDuel began offering free prop contests during the Democratic debates earlier this year involving Biden and U.S. Sen. Bernie Sanders, said Mike Raffensperger, FanDuel's chief marketing officer.

"We're thrilled with customers' appetite to use culture at large as an opportunity to compete with others for a chance to win cash," he said, noting the company has hosted similar contests involving reality TV shows.

While some debate watchers will engage in drinking games, taking a slug every time a particular candidate says or does a particular thing, Marino will be waiting for the first time Trump gives Biden a nickname.

"He's definitely going to call him 'Sleepy Joe,'" Marino predicted.