Katy Perry can be "bitch" when she is tired.
The 'California Gurls' singer - who is engaged to Russell Brand - admits she gets grouchy if she doesn't have enough sleep, but believes her fans like her "outspoken" nature.
She said: "I can do bitchy. Give me six hours of sleep instead of eight and I'll show you the bitch in me.
"I've always been outspoken and I'm not easily influenced. My views are unsolicited, unfiltered and that's why people never know what they're going to get - there's some spice because it's spontaneous."
The 25-year-old pop star also admits she and Russell like to do normal things together and wear specific outfits when they want to go out in public.
She explained to The Sun newspaper: "My boyfriend and I go bike-riding all the time. We go to the movies and don't have to rent the theatre out.
"There's a certain magnet that you turn on and off - it's called hat and sunglasses, and not wearing glittery outfits."
Although Katy enjoys being famous she is adamant it wasn't her goal when she began her pop career - she just wanted to make music people liked.
She said: "It's all about balance. A lot of people in the spotlight mix celebrity with music, but when I was growing up, I didn't dream about the lifestyles of the rich and famous.
"I just wanted to f***ing sing songs, play shows and perform in front of massive audiences. That was my dream."