Band member Siva Kaneswaran told Digital Spy that the 17-year-old superstar was a notorious prankster when they supported him in London and South America earlier this year.
"The first time we met Justin he shot us in the face with an air gun," Kaneswaran explained. "We walked in and said 'hi' and then he shot me and Nathan in the face!
"After, me and Jay went under the stalls in the O2 Arena because you touch people's ankles and [we] were taking girls' shoes off and having a laugh.
"Justin then came over and took out his mic stand and started bashing ankles! I thought, 'If these girls knew it was their idol giving them bruises on their ankles they'd go crazy!'"
The 'Lightning' star also said that the band would love to support Bieber in the US after touring with him earlier this year.
"After we supported Justin Bieber in London his manager asked us to go on the road with him through South America," Kaneswaran revealed.
"He put us on the whole tour, but we couldn't go because we had the singles to put out and the album to finish up.
"We only managed to do two dates in South America in the end, but if he calls again we'd definitely go and support him on his US tour."
The Wanted's new album Battleground is available to buy now.
> The Wanted: 'New album Battleground has an international feel'
Watch The Wanted's new music video for 'Warzone' below: