Paris Hilton stole her famous catchphrase "that's hot" from her sister Nicky Hilton Rothschild.
The 38-year-old socialite has confessed that the compliment was something her younger sibling used to say all the time - but she subsequently claimed copyright for it.
She told Vogue: "I started making shirts that said, 'That's hot', and on the back they said, 'You're not.' It was cute.
"'That's hot' was something that my sister always used to say, but I trademarked it and I own it. Sorry, Nicky."
Meanwhile, the hotel heiress also claimed that she and pal Nicole Richie's reality show 'The Simple Life' was responsible for making Juicy Couture fashionable, as she started a trend which everyone from Kim Kardashian West to Madonna soon copied.
She said in a video interview with the fashion publication: "They didn't say where we were going, so I didn't even know what to pack.
"I basically packed all of my favourite outfits - included a lot of Juicy, a lot of pink, a lot of heels.
"Juicy is something that we wore almost every single day because we are always having to do these jobs. We didn't wanna just be in like overalls or jeans. We wanted to be comfortable and cute.
"When we shot the show, I had no idea how huge it would be.
"I remember after 'The Simple Life' aired, all of the sudden I started seeing Juicy Couture everywhere.
"When you looked through any tabloid, everyone was rocking them."
Paris considers herself to be a fashion "chameleon" - meaning she adjusts her style depending on her surroundings.
She said: "I do have a signature look - I love pink and I love sparkles - but my style has changed over the years.
"I have been really influenced by my sister Nicky, whose style has always been the complete opposite of mine.
"I've learned to tone it down a little bit, be a little bit more understated sometimes. But it depends on the situation; I'm a chameleon.
"I can show up in a Chanel suit, looking like a businesswoman, but if I'm at a party or Halloween or Burning Man, then I'm going all out."