Lorde says a vicious fight with her sister in a Las Vegas hotel room left her with a scar down her left arm.
Lorde told the crowd gathered for last night's Taite Music Prize the story while detailing her achievements over the past year - including having to "go on stage when you're really mad about something".
Lorde, who often tours with family members, said the fight with her older sister started because the pair were "tired and really sick".
"Because I'm not old enough to go out and rave I'm just in my hotel room in Vegas," Lorde told the crowd gathered at Galatos in Auckland last night.
"Me and my older sister were there and we were really tired and really sick, and we had a fight.
"She actually scratched a bit out of my arm, which I still have the scar from. Now I can go on stage following stuff like that, so it's cool."
Watch Lorde speak about the incident in the livestream below (Lorde's speech starts at the 1 hour 25 minute mark):
Lorde made her entertaining speech before the awards announcement, which was given to Jakob for their fourth album Sines.
Read more: Pain worth it for Taite prizewinners Jakob
In her speech, Lorde gave shout-outs to her favourite local artists, including Electric Wire Hustle, Tom Scott, SJD, Tiny Ruins and Grayson Gilmour.
She also poked fun at her image as a pop superstar, saying in New Zealand, "I'm about as far from an underdog as you can get, sitting in my pop castle in Morningside, churning out hits, drinking the blood of Six60 for strength".
And she detailed an embarrassing moment when she got starstruck meeting Prince, saying the musician has a "funny effect on people".
She said the superstar sidled up to her unseen and whispered in her ear: "So good to see you here."
Lorde turned to reply "good to see you, too" but blurted out, "Oh my God!" at him.
She said she had learnt a lot over the past year, including how to "play a show" and wash her underwear in hotel sinks.
"I've learnt how to play a show. That doesn't sound like a particularly big thing but I went from not being the kind of person who would not know how to entertain a room full of people to just being so happy and so comfortable on stage and having such a good time every night and going to play these crazy festivals in Atlanta or Portugal or California or wherever and it being such a cool thing for me ...
"I've gotten really good at hand-washing my undies in hotel bathrooms. I can do just about anything on four hours' sleep and an energy drink."
Lorde is believed to be working on the follow-up to her debut album, Pure Heroine, with producer Joel Little in Auckland.
Pure Heroine was the 10th highest-selling album of 2014, it was revealed today, with sales of two million. No. 1 was the Frozen soundtrack, with 10 million sales.