Nick and Joe Jonas.Photo: Matthew Stockman/Getty Images

Nick Jonas and Joe Jonas

Joe Jonasrocked a very interesting choice of attire on Friday while attending the U.S. Open with brotherNick Jonas.

As the two brothers watchedRafael Nadal take the court, Joe, 30, was photographed wearing aJustin Biebershirt, which depicted the Canadian pop star wearing Jonas Brother apparel.

The image portrayed on Joe’s shirt appeared to be taken from one of Bieber’s outings over the summer, when the 25-year-old singer was spotted in West Hollywood wearing a shirt with athrowback photo of the groupon it, which was from his ownclothing line, Drew.

Although Joe’s choice of apparel could be a sign of the pair’s mutual affection for one another, it could also be a sign that Bieber has become the latest celebrity to join the Jonas brothers in alight-hearted prank war.

(L-R) Nick Jonas and Joe Jonas.Larry Marano/Shutterstock

Nick Jonas and Joe Jonas

In February, Nick, 26, kicked off a prank war with actorJohn Stamos, who had been spotted several times over the years wearing Jonas Brother T-shirts.

Taking notice, Nick stepped out wearing a sweatshirt that had a photo on it of theFuller Housestar wearing a JoBros T-shirt.

“It’s your move@johnstamos,” he wrote, sharing the photo on Instagram.

John Stamos.Paul Morigi/Getty

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Escalating things even further, theYouactor even appeared to get anapparent tattoo of Nick’s face on his arm. “#jobrosforlife,” he captioned an Instagram photo of his tattoo artist getting to work.

Stamos even got Joe in on the fun after the actor chimed in with his ownextra special song request.

Before the group embarked on their Happiness Beings tour earlier this year, Joe made a post on Instagram asking fans which songs they’d most like to see the group perform.

Choosing a number that’s very much outside their repertoire, Stamos suggested “Forever!” a reference to the Beach Boys classic his character Uncle Jesse sings to his wife during their wedding ceremony.

source: people.com