Those types of bets can be placed abroad with sportsbooks like BetUS, which is based in Costa Rica and potentially the Canadian province of Ontario. BetMGM public relations manager John Ewing said he was waiting to hear from Canadian authorities about whether such bets will be okay.

But in the United States, where betting laws vary from state to state, the general rule is that betting is limited to what happens on the field. A handful of states allow bets to be placed on the color of the Gatorade thrown at the winning trainer (red or pink is this year's +260 favorite at FanDuel Sportsbook), but even that type of bet is not allowed in Las Vegas.

Las Vegas, the longtime epicenter of sports betting in the US, has some of the strictest rules regarding the types of bets placed.

Swift's romance with Kelce became one of the breakout stories of this NFL season and she has attended several Chiefs games, including their AFC championship game victory in Baltimore on Sunday, where she joined the team for his celebration on the field and welcomed Kelce with a kiss Since he will be performing in Japan on Super Bowl weekend, fans began to wonder if he will travel to Las Vegas to see Kelce and Kansas City take on the San Francisco 49ers.

It seems natural that they can bet money in Las Vegas.

However, as a matter of principle, Ewing said it makes sense to not allow bets on things other than the action on the field, such as the length of the national anthem.

“We don't want any subjectivity in a prop (bet),” Ewing said. “We want it to either win or not win, or go above or below, and that is also the concern of the regulators. That’s why we typically stick to the fact that if it’s in the box score, it can be published.”