A woman has been caught on camera hitting a man who grabbed her breast at Rhythm & Vines.
Madeline Anello-Kitzmiller was walking topless through the crowd with her chest painted in glitter from a festival stall.
Footage of an unknown man creeping up behind her and touching her breast before running away was uploaded to Facebook on Monday.
The video shows Ms Anello-Kitzmiller storming over to him and hitting him on the head, while her friend throws a drink in his face.
By Monday night, the video of the incident had been viewed and shared hundreds of thousands of times. Facebook eventually removed the clip for breaching its rules.
The 20-year-old American told NZME she was surprised by the reaction she received for going topless.
"Within five minutes, we were being told we were disgusting, people were yelling 'put a shirt on'. I couldn't believe it. It was just as much girls as it was guys.
"It was quite shocking. I'm used to love and kindness, freedom of expression, equality."
She said people are more liberal at festivals in her hometown of Portland, Oregon.
Rhythm and Vines spokesperson Chris Henry told NZME he wasn't aware of the incident.