There are prop bets for just about everything on the Super Bowl, but a betting site has reported noticing some suspicious betting activity concerning a grunge-related Super Bowl prop bet with the betting favorite shifting overnight leading into Friday (Feb. 6).

What does grunge have to do with the Super Bowl? While there are no grunge acts set to play at the culmination of the recent football season, one of this year’s teams — the NFC champion Seattle Seahawks — hail from Seattle which many view as the ceremonial home for the ’90s grunge movement.

As TV networks tend to play music bumpers leading into commercial blocks sometimes representative of one of the teams, it’s expected that there will be one of the Seattle “Big 4” of Pearl Jam, Soundgarden, Nirvana or Alice in Chains played during one of these bumpers leading into a commercial block.

What Is Happening With the Grunge Super Bowl Prop Bet?

Per BetOnline, wagering leading into Friday had Pearl Jam as the favorite band to be the first grunge music bumper played at +150 odds. They were followed by Nirvana at +200, Alice in Chains at +400 and Soundgarden as the long shot at +800.

But as of Friday morning, things have changed significantly with most of the betting action now coming in on Soundgarden, who are listed at -150. Pearl Jam has shifted to +270, Nirvana to +500 and Alice in Chains at +725.

READ MORE: The Best Song Off Every ‘Big 4’ Grunge Album

Per a press release issued by BetOnline, they characterized the change as “suspicious wagering,” adding that “maybe someone knows something on that front.”

Though there has been no public confirmation of whether or not a grunge song from Seattle’s ‘Big 4″ will be played and when, there is always the possibility of a leak. Whether that is what is happening with the betting shift here remains to be seen.

What Other Super Bowl Music Prop Bets Are There?

BetOnline noted that none of the other music related prop bets so far seem to indicate any leaks. These would be related to the prop bets surrounding halftime performer Bad Bunny, National Anthem singer Charlie Puth and the pre-Super Bowl performance of Bay Area rockers Green Day.

The primary Green Day prop bet centers on which will be the first song performed by the group during their appearance. The current frontrunner is “American Idiot” at +100, followed by “Basket Case” at +300 and “Know Your Enemy” at +400.

Looking for a long shot? “Wake Me Up When September Ends” is listed at +2000 and “She” and “Brain Stew” both at +1400.

For Bad Bunny, there are a wealth of betting options from whether he will wear a dress to his primary hair color and even which artists will be special guests during the halftime show. Get a closer look at some of the prop bets through the BetOnline website.

See a gallery of rock and metal acts that have voiced their support for Bad Bunny playing the Super Bowl halftime below.