One Direction's Liam Payne got a shock while changing after a gym session in New York when he discovered a fan had sneaked in to have a peek.
The boys are back in the US thrilling fans on tour, and have been hitting the weights in an exclusive fitness club while staying in the Big Apple.
But one female fan managed to sneak past security guards and poor Liam got a shock when he was towelling himself down and discovered the young fan was in the same room.
A source told The Sun: "Liam was stunned when he saw her in the changing room - he couldn't believe she'd got past security.
"For one thing, he was in the middle of getting dressed and had no idea what she was going to do, as their fans in the US are mad."
The girl was reportedly swiftly booted out by the band's bouncers.
Liam's bandmate Niall Horan recently admitted that their crazed devotees can sometimes be a bit "too much" - and that it's shocking to see girls break down and cry at gigs.
He told Digital Spy: "Sometimes I've seen some stuff that's a bit too much! Also, sometimes they'll queue outside a venue for ages for us in the freezing cold. Queuing tips for fans: wrap up and bring food!
"You can see girls getting too excited and they start crying or worse. In a lot of these countries they don't get a lot of gigs to go to, so when they get to see their favourite artist they take full advantage of it. Obviously the excitement builds up too much for some on the night and they get a bit... crazy."