Once upon a time, only the most diehard of Taylor Swift fans could be said to be interested in the pop star's choices at the concession stand.

Now, you can bet on it. Yes, it's true: This coming Super Bowl Sunday, the odds are 12-to-1 that the biggest pop superstar of our era will be shown holding and eating a hot dog.

The tectonic collision of the NFL and Taylor Swift, two of the biggest entertainment powerhouses in the U.S., dominated TV screens this fall as Swift began dating Travis Kelce, the star tight end for the Kansas City Chiefs.

Now, with 115 million Americans or more poised to watch Kelce's Chiefs take on the San Francisco 49ers on Feb. 11, sportsbooks are looking for their bite at the publicity apple.

Super Bowl proposition bets — wagers about the game that aren't directly tied to the final outcome — have always been popular. This year, they've become a sideshow and a circus all their own. Call it the Taylor Swift effect.

How many times will the pop queen be shown during the game? Will she wear white, red or a longshot color? Which Swift song will the CBS broadcast team play first? And, of course, the big one: Will Kelce propose to her at the game? (Incredibly, the online sportsbook BetUS puts the odds at just 6-to-1.)

Who dreams up these Super Bowl prop bets?

When sportsbook oddsmakers set out to create a slate of prop bets for each year's Super Bowl, identifying storylines is always the first step, said Dave Mason, brand manager at the online sportsbook BetOnline.

"Of course, this year, the creme de la creme fell into our laps," he said.

Bettors can wager on 89 Swift-related prop bets on BetOnline in an homage to the singer's birth year and platinum record 1989. The company projects this year to be the most-bet Super Bowl in the book's 25-year history.

Swift, Kelce and the Chiefs have become the subject of right-wing conspiracy theories that allege the NFL has been rigged in order to promote Democrats.

The sportsbooks haven't shied from politics, either: BetOnline puts the odds at 3-to-1 that former President Donald Trump will mention the singer on TruthSocial on Super Bowl Sunday, while BetUS gives it 10-to-1 odds that Swift endorses Biden after the game.

Once the Chiefs advanced to the Super Bowl with a win over the Baltimore Ravens in last week's AFC Championship Game, the sportsbook's oddsmakers set out to brainstorm ideas for wagers. (That process included a post by the company's sportsbook manager on the social media site X soliciting ideas for props, with a promised reward of $100 in cash.)

"We challenged ourselves to come up with the biggest menu of Taylor Swift prop bets in the world. We figured since she sets the bar when it comes to entertainment, we had to do the same for our industry," Mason said.

The results run the gamut from the Super Bowl and beyond: What color dress will Swift wear at this weekend's Grammy Awards? Will she drink champagne at a Super Bowl after-party? Which will have more diamond carats, a Chiefs Super Bowl ring or Swift's engagement ring?

Prop bets are designed to help draw in casual fans

Ever since a Supreme Court decision in 2018 opened the door for nationwide legalization, sports gambling is now legal in 38 states and the District of Columbia, the American Gambling Association reports.

The prop bets are designed to get casual fans "to try signing up and placing a bet for fun with a way to entice them and maybe get them to come back," said Stephen Shapiro, a professor of sport and entertainment management at the University of South Carolina.

"It's a way to draw people in. And so this Taylor Swift component, I think, brings an additional opportunity," Shapiro said.

The NFL and sportsbooks should seek a balance between marketing and revenue opportunities while not drawing individuals into problem gambling, he added. (About 2 million Americans are thought to have a severe gambling problem, according to the National Council on Problem Gambling.)

Sportsbooks based in the U.S. are generally restricted to offering prop bets that are related to the game itself, like how many touchdowns Kelce might score, or whether the 49ers will receive the opening kickoff. (Such restrictions help ensure that bets have an objective outcome that bettors and sportsbooks alike can rely on, like the box score, Shapiro said.)

For Taylor Swift bets and other wagers like them, bettors must turn to sportsbooks based outside the U.S., many of which are not regulated by government agencies and may be illegal to place a wager with, depending on the state. Prop bet wagers that aren't related to the game are often capped at $100 or less.

Taylor Swift's appearance at Super Bowl LVIII isn't yet confirmed

Swift has made a powerful argument for being the world's biggest pop star. Her 2023 was a supersized year, thanks to her record-breaking Eras Tour, the first concert tour to gross more than a billion dollars. Even the accompanying concert film netted $261 million at box offices worldwide, good for the highest-grossing concert movie of all time.

A YouGov poll conducted this week found that more than half of Americans had a favorable opinion of her, higher than the president who is reportedly hoping to win her endorsement. And 6 percent — the equivalent of 20 million people — described themselves as "a major fan" of hers.

Any Super Bowl prop bets depend on whether Swift will be at the game at all. Her attendance has not yet been publicly confirmed.

On Saturday night before the Super Bowl, Swift is scheduled to perform a concert in Tokyo. Lest you wonder whether that's enough time for her to make it to Las Vegas for the game, worry not, the Embassy of Japan said Friday.

"Despite the 12-hour flight and 17-hour time difference, the Embassy can confidently speak now to say that if she departs Tokyo the evening after her concert, she should comfortably arrive in Las Vegas before the Super Bowl begins," the embassy said in a statement on its social media accounts.